Everyone else answered your technical question, I’ll just say that the f/1.2 lenses are usually found on 56mm or 75mm lenses, which give them the same look as an 85 f/1.8 and 112 f/1.8 respectively.

These are still very capable portrait lenses… and while you would notice a difference side-by-side with full frame lenses, it will be slight. Reviews and sample images:

Viltrox 75mm f/1.2: https://sonyalpha.blog/2023/10/18/viltrox-75mm-f1-2/ vs. Sigma 105 f/1.4 (FF): https://sonyalpha.blog/2018/10/16/sigma-105mm-f-1-4-dg-hsm-art/