When I try to open C:\Windows\system32\inetsrv\config\schema\IIS_schema.xml
for example on Windows 10 Pro, build 20H2, I can always open it in notepad, but if I open it in gvim (a real editor) it pretends like the file doesn't exist.
I've even run gvim as a domain administrator and it still makes like it doesn't exist. I've never seen this sort of behavior before, it's really strange.