Example of custom order field in graphql without reloadind the order

Model/Resolver/OrderCustomField.php

@@ -0,0 +1,29 @@
+<?php
+/**
+ * Copyright © MageWorx. All rights reserved.
+ * See LICENSE.txt for license details.
+ */
+declare(strict_types=1);
+
+namespace MageWorx\ExtendedCartGraphQl\Model\Resolver;
+
+use Magento\Framework\Exception\LocalizedException;
+use Magento\Framework\GraphQl\Config\Element\Field;
+use Magento\Framework\GraphQl\Schema\Type\ResolveInfo;
+
+class OrderCustomField implements \Magento\Framework\GraphQl\Query\ResolverInterface
+{
+    /**
+     * @inheritDoc
+     */
+    public function resolve(Field $field, $context, ResolveInfo $info, array $value = null, array $args = null)
+    {
+        if (!isset($value['model'])) {
+            throw new LocalizedException(__('"model" value should be specified'));
+        }
+        /** @var \Magento\Sales\Api\Data\OrderInterface $order */
+        $order = $value['model'];
+
+        return (string)$order->getData('your_custom_field');
+    }
+}

etc/schema.graphqls

@@ -8,3 +8,7 @@ input SetPaymentMethodOnCartInput {
     @resolver(class: "MageWorx\\ExtendedCartGraphQl\\Model\\Resolver\\CustomFieldOnPaymentMethod")
     @doc(description: "Add custom field to payment method mutation and save it somwhere in DB")
 }
+type CustomerOrder {
+    my_custom_field: String
+    @resolver(class: "MageWorx\\ExtendedCartGraphQl\\Model\\Resolver\\OrderCustomField")
+}