1) start with 80+ war support. War score is your war support + a score for each foreign territory you hold (does anyone know the numbers on that? In the attached screenshot I get a lot for holding the capital, but comparing it with other situations, the value for holding that seem volatile). Being militarist and some religious tenets help with getting this up.
2) get some of the demands, either the faith one or the influence ones and press them. Each territory you have such a claim on is just 10 war score compared to 40 for ones you have no reason to take.
3) as each territory and city you hold decreases enemy war support, once and per turn. Pillaging stuff on the other hand raises their war support. As the opponent surrenders at 0 support, try to keep it above 10 until you‘ve conquered some stuff.
4) once the enemy is close to 0 but not at 0, they can send you surrender terms. You can ignore them, accept them or refuse them. If you refuse, they gain +8 war support, which can prolong the war per 1 or 2 turns. They send these offers repeatedly. Granted, this does really only help in smaller wars as each city you hold is -4 per turn for them.
The system takes some time to get used to, but it is quite neat once you understand it mechanically and also have an immersive vision of what the terminology is supposed to mean. I also like that even for a very militaristic approach, you need to be reasonably strong in not just that aspect of the game.
that said, I hope for a little bit of flexibility: pay (much) influence to continue a war for some turns after the opponent surrendered. Pay (even) more influence for taking more than your warscore allows. Increase the stability penalty from having negative influence.