There is a way to find the .dll on Windows, using the built in NuGet Package Manager that comes with Visual Studio 2022.
Open Visual Studio 2022->NuGet Package Manager. Search for and install the WebView2 package.
A new directory will be generated at the root of the visual studio project, and the .dll file will be found within.
Copy this to the same folder that your plugin’s .exe or .vst3 file is generated. Make sure you have WebView2RuntimeLoader installed.