I set up my sag depending on the type of riding I’ll be doing with my bike. If I’m XC lightweight racer type bike then 20% sag max is all that is needed, but I’d be using an 80-100mm max travel fork for that. If I’m all day riding trail type stuff then 20-25% max sag with a 100-130mm max travel fork and then if I have a big travel fork then I’m obviously wanting it for big hits and not an all day ride, I want plush performance so 30-40% on forks with 150mm + travel. Measure the sag with your weight, with pack on your back, sat on the bike. If I then want to reduce brake dive then I’d adjust the compression dampening, and the same with rebound.
Right travel for the task and right set-up for the terrain.