Saw these replies earlier but wanted to jump in since I have been shooting portraits for over a decade. Honestly, while the f/2 macro is fine for hobbyists, if you are doing professional senior sessions then autofocus reliability is your bread and butter. I have tried many lenses over the years and would skip the adapter route entirely because you just dont want that stress during a paid session. Instead, look into the Canon RF 100mm f/2.8 L Macro IS USM. Yeah, it is a bit more than the f/2, but it is absolute professional L-series glass that wont let you down. The compression at 100mm is actually cleaner for portraits than 85mm anyway, and the reliability you get from native RF glass is worth every penny when you actually have a client waiting on you.

Regarding what #1 said about the 85mm f/1.2 being a beast, they are totally spot on! Honestly though, if you want that sharp look without the stress, look at the Canon RF 85mm f/2 Macro IS STM. It is super lightweight and the autofocus on the R6 is incredible with it. You'll save a ton of cash for other gear like a new Godox V1 Flash which will do way more for your portraits than an expensive lens ever could!

Honestly, the 85mm f/1.2 is a beast, but you really dont need to drop that kind of money to get professional results for senior portraits. Ive shot with adapted glass for years and the autofocus miss rate is usually overblown if your firmware is updated, though it can be a gamble in tricky, low-light Seattle weather. If you want a solid middle ground, look at the native f/2 prime glass. It is much lighter, way easier on the wallet, and honestly, the sharpness is usually more than enough for portrait work. Just be careful with third-party adapters because they can sometimes cause weird micro-stutters that ruin a shot. Whatever you choose, just make sure you rent it for a test session first before locking in the purchase.