So coming from EU4 where you grab chunks of land with a simple CB (or even no CB), I am still a bit confused on how land expansion through conquest works and I need some clarification, even though Ive watched a few vids on ck2 basics.

To get this straight, if you fabricate a claim on a province and use that claim as CB you are only allowed to get that specific province no matter what or how much enemy territory you occupy? Also you need to have always 100% to win a a war?

So for a bigger land grab the best way, excluding the Holy War CB, would be to try create or get a better "de jure" title from the one you already have so you can get a "de jure" claim on the whole region accordingly (duchy, kingdom, empire) which will allow you to get more provinces in a single war, correct?