Sample Item template for VS2022 showing how to include multiple files.
To test, you can simply download the files to a folder called FullRazorComponent (name is not important) in %USERPROFILE%\Documents\Visual Studio 2022\Templates\ItemTemplates
You can then customise the .razor, .cs, .css, .ico to suit - and if you want, you can edit the vstemplate to change the name/description