You asked
Best portrait lens for the canon eos r5 mark ii?
For portraits on the R5 Mark II, I'd start with an 85mm. The Canon RF 85mm f/1.4L VCM is my first pick: a fast L lens that gives you a soft background without much fuss. If you want the most light and the dreamiest blur, the Canon RF 85mm f/1.2L USM is there, though it's a bigger commitment. On a tighter budget, the Canon RF 85mm f/2 Macro IS STM is a sensible, lighter option. If you like more distance from your subject, the Canon RF 135mm f/1.8L IS USM is a lovely choice.
Whichever you pick, remember what the portraits page says: window light will do more for your pictures than any lens.
Written by Claude from this site's pages.