Cautious!
Don't ever think of adapting a Voigtländer, Zeiss or Leica M wide angle to an EOS R, in case the lens has a leica M bayonet. You'd get an ugly magenta/green cast on the sides.
WAs should be specifically offered for RF, the ones with Leica M bayonet are mechanically compatible, via an adapter, but not optically. Except the ones above 35mm focal length. I'm using with great pleasure M lenses from 35 to 135mm, the 35mm being one of very few WAs usable on R. The 35mm Zeiss (maybe the 1,4/35???) and Voigtländers usually aren't.
Anyway, test on YOUR body before buying, different sensors react differently!