diff --git a/output/openapi/elasticsearch-openapi.json b/output/openapi/elasticsearch-openapi.json
index 433f39a862..ab7bacf3c0 100644
--- a/output/openapi/elasticsearch-openapi.json
+++ b/output/openapi/elasticsearch-openapi.json
@@ -63336,7 +63336,7 @@
             "type": "boolean"
           },
           "subobjects": {
-            "type": "boolean"
+            "$ref": "#/components/schemas/_types.mapping:Subobjects"
           },
           "_data_stream_timestamp": {
             "$ref": "#/components/schemas/_types.mapping:DataStreamTimestamp"
@@ -64663,7 +64663,7 @@
                 "type": "boolean"
               },
               "subobjects": {
-                "type": "boolean"
+                "$ref": "#/components/schemas/_types.mapping:Subobjects"
               },
               "type": {
                 "type": "string",
@@ -64675,6 +64675,14 @@
           }
         ]
       },
+      "_types.mapping:Subobjects": {
+        "type": "string",
+        "enum": [
+          "true",
+          "false",
+          "auto"
+        ]
+      },
       "_types.mapping:PassthroughObjectProperty": {
         "allOf": [
           {
diff --git a/output/openapi/elasticsearch-serverless-openapi.json b/output/openapi/elasticsearch-serverless-openapi.json
index 7a5e27ebe4..d0e2a9bc54 100644
--- a/output/openapi/elasticsearch-serverless-openapi.json
+++ b/output/openapi/elasticsearch-serverless-openapi.json
@@ -41003,7 +41003,7 @@
             "type": "boolean"
           },
           "subobjects": {
-            "type": "boolean"
+            "$ref": "#/components/schemas/_types.mapping:Subobjects"
           },
           "_data_stream_timestamp": {
             "$ref": "#/components/schemas/_types.mapping:DataStreamTimestamp"
@@ -42330,7 +42330,7 @@
                 "type": "boolean"
               },
               "subobjects": {
-                "type": "boolean"
+                "$ref": "#/components/schemas/_types.mapping:Subobjects"
               },
               "type": {
                 "type": "string",
@@ -42342,6 +42342,13 @@
           }
         ]
       },
+      "_types.mapping:Subobjects": {
+        "type": "string",
+        "enum": [
+          "true",
+          "false"
+        ]
+      },
       "_types.mapping:PassthroughObjectProperty": {
         "allOf": [
           {
diff --git a/output/schema/schema-serverless.json b/output/schema/schema-serverless.json
index 1b0d463b80..0cdc25eb20 100644
--- a/output/schema/schema-serverless.json
+++ b/output/schema/schema-serverless.json
@@ -90415,7 +90415,7 @@
           }
         }
       ],
-      "specLocation": "_types/mapping/complex.ts#L58-L63"
+      "specLocation": "_types/mapping/complex.ts#L59-L64"
     },
     {
       "inherits": {
@@ -90684,7 +90684,7 @@
           }
         }
       ],
-      "specLocation": "_types/mapping/complex.ts#L25-L36"
+      "specLocation": "_types/mapping/complex.ts#L26-L37"
     },
     {
       "inherits": {
@@ -90741,7 +90741,7 @@
           }
         }
       ],
-      "specLocation": "_types/mapping/complex.ts#L38-L43"
+      "specLocation": "_types/mapping/complex.ts#L39-L44"
     },
     {
       "inherits": {
@@ -90773,8 +90773,8 @@
           "type": {
             "kind": "instance_of",
             "type": {
-              "name": "boolean",
-              "namespace": "_builtins"
+              "name": "Subobjects",
+              "namespace": "_types.mapping"
             }
           }
         },
@@ -90787,7 +90787,24 @@
           }
         }
       ],
-      "specLocation": "_types/mapping/complex.ts#L45-L49"
+      "specLocation": "_types/mapping/complex.ts#L46-L50"
+    },
+    {
+      "esQuirk": "This enum is a boolean that evolved into a tri-state enum. True and False have\nto be (de)serialized as JSON booleans.",
+      "kind": "enum",
+      "members": [
+        {
+          "name": "true"
+        },
+        {
+          "name": "false"
+        }
+      ],
+      "name": {
+        "name": "Subobjects",
+        "namespace": "_types.mapping"
+      },
+      "specLocation": "_types/mapping/TypeMapping.ts#L63-L74"
     },
     {
       "inherits": {
@@ -90844,7 +90861,7 @@
           }
         }
       ],
-      "specLocation": "_types/mapping/complex.ts#L51-L56"
+      "specLocation": "_types/mapping/complex.ts#L52-L57"
     },
     {
       "kind": "interface",
@@ -117753,8 +117770,8 @@
           "type": {
             "kind": "instance_of",
             "type": {
-              "name": "boolean",
-              "namespace": "_builtins"
+              "name": "Subobjects",
+              "namespace": "_types.mapping"
             }
           }
         },
diff --git a/output/schema/schema.json b/output/schema/schema.json
index 74f7debb82..8807ae93ff 100644
--- a/output/schema/schema.json
+++ b/output/schema/schema.json
@@ -75289,7 +75289,7 @@
           }
         }
       ],
-      "specLocation": "_types/mapping/complex.ts#L58-L63"
+      "specLocation": "_types/mapping/complex.ts#L59-L64"
     },
     {
       "kind": "interface",
@@ -77212,7 +77212,7 @@
           }
         }
       ],
-      "specLocation": "_types/mapping/complex.ts#L25-L36"
+      "specLocation": "_types/mapping/complex.ts#L26-L37"
     },
     {
       "kind": "interface",
@@ -78479,7 +78479,7 @@
           }
         }
       ],
-      "specLocation": "_types/mapping/complex.ts#L38-L43"
+      "specLocation": "_types/mapping/complex.ts#L39-L44"
     },
     {
       "kind": "interface",
@@ -78634,8 +78634,8 @@
           "type": {
             "kind": "instance_of",
             "type": {
-              "name": "boolean",
-              "namespace": "_builtins"
+              "name": "Subobjects",
+              "namespace": "_types.mapping"
             }
           }
         },
@@ -78648,7 +78648,7 @@
           }
         }
       ],
-      "specLocation": "_types/mapping/complex.ts#L45-L49"
+      "specLocation": "_types/mapping/complex.ts#L46-L50"
     },
     {
       "kind": "enum",
@@ -78721,7 +78721,7 @@
           }
         }
       ],
-      "specLocation": "_types/mapping/complex.ts#L51-L56"
+      "specLocation": "_types/mapping/complex.ts#L52-L57"
     },
     {
       "kind": "interface",
@@ -80135,6 +80135,33 @@
       ],
       "specLocation": "_types/mapping/core.ts#L202-L204"
     },
+    {
+      "kind": "enum",
+      "esQuirk": "This enum is a boolean that evolved into a tri-state enum. True and False have\nto be (de)serialized as JSON booleans.",
+      "members": [
+        {
+          "name": "true"
+        },
+        {
+          "name": "false"
+        },
+        {
+          "availability": {
+            "stack": {
+              "featureFlag": "sub_objects_auto",
+              "since": "8.16.0",
+              "visibility": "feature_flag"
+            }
+          },
+          "name": "auto"
+        }
+      ],
+      "name": {
+        "name": "Subobjects",
+        "namespace": "_types.mapping"
+      },
+      "specLocation": "_types/mapping/TypeMapping.ts#L63-L74"
+    },
     {
       "kind": "interface",
       "name": {
@@ -80822,8 +80849,8 @@
           "type": {
             "kind": "instance_of",
             "type": {
-              "name": "boolean",
-              "namespace": "_builtins"
+              "name": "Subobjects",
+              "namespace": "_types.mapping"
             }
           }
         },
diff --git a/output/typescript/types.ts b/output/typescript/types.ts
index 64c8d9d5af..1dfc00525c 100644
--- a/output/typescript/types.ts
+++ b/output/typescript/types.ts
@@ -5711,7 +5711,7 @@ export interface MappingNumberPropertyBase extends MappingDocValuesPropertyBase
 
 export interface MappingObjectProperty extends MappingCorePropertyBase {
   enabled?: boolean
-  subobjects?: boolean
+  subobjects?: MappingSubobjects
   type?: 'object'
 }
 
@@ -5843,6 +5843,8 @@ export interface MappingSparseVectorProperty extends MappingPropertyBase {
   type: 'sparse_vector'
 }
 
+export type MappingSubobjects = boolean | 'true' | 'false' | 'auto'
+
 export interface MappingSuggestContext {
   name: Name
   path?: Field
@@ -5905,7 +5907,7 @@ export interface MappingTypeMapping {
   _source?: MappingSourceField
   runtime?: Record<string, MappingRuntimeField>
   enabled?: boolean
-  subobjects?: boolean
+  subobjects?: MappingSubobjects
   _data_stream_timestamp?: MappingDataStreamTimestamp
 }
 
diff --git a/specification/_types/mapping/TypeMapping.ts b/specification/_types/mapping/TypeMapping.ts
index 37aae9188b..c36e42dde0 100644
--- a/specification/_types/mapping/TypeMapping.ts
+++ b/specification/_types/mapping/TypeMapping.ts
@@ -48,7 +48,7 @@ export class TypeMapping {
   _source?: SourceField
   runtime?: Dictionary<string, RuntimeField>
   enabled?: boolean
-  subobjects?: boolean
+  subobjects?: Subobjects
   /**
    * @availability stack since=7.16.0
    * @availability serverless
@@ -59,3 +59,16 @@ export class TypeMapping {
 export class DataStreamTimestamp {
   enabled: boolean
 }
+
+/**
+ * @es_quirk This enum is a boolean that evolved into a tri-state enum. True and False have
+ *   to be (de)serialized as JSON booleans.
+ */
+export enum Subobjects {
+  true,
+  false,
+  /**
+   * @availability stack since=8.16.0 visibility=feature_flag feature_flag=sub_objects_auto
+   */
+  auto
+}
diff --git a/specification/_types/mapping/complex.ts b/specification/_types/mapping/complex.ts
index 4cbb2a4f64..3f83b38aae 100644
--- a/specification/_types/mapping/complex.ts
+++ b/specification/_types/mapping/complex.ts
@@ -21,6 +21,7 @@ import { TimeSeriesMetricType } from '@_types/mapping/TimeSeriesMetricType'
 import { double, integer } from '@_types/Numeric'
 import { CorePropertyBase, IndexOptions } from './core'
 import { PropertyBase } from './Property'
+import { Subobjects } from './TypeMapping'
 
 export class FlattenedProperty extends PropertyBase {
   boost?: double
@@ -44,7 +45,7 @@ export class NestedProperty extends CorePropertyBase {
 
 export class ObjectProperty extends CorePropertyBase {
   enabled?: boolean
-  subobjects?: boolean
+  subobjects?: Subobjects
   type?: 'object'
 }