The dll-file is obtained from the NuGet package microsoft.web.webview2
https://nuget.info/packages/Microsoft.Web.WebView2/1.0.1150.38
located in the sub-folder build/native/x64

For full API compatibility, this Release version of the WebView2 SDK
requires WebView2 Runtime version 99.0.1150.38 or higher:
https://learn.microsoft.com/en-us/microsoft-edge/webview2/release-notes/archive?tabs=dotnetcsharp#10115038