

In CK3 you gain a Casus Belli by fabricating a claim or by unlocking perks like Forced Vassalization and Ducal Conquest. In Crusader Kings 3 you need to have a Casus Belli available so you expand in a more “direct” manner than just playing nice or seducing queens. You have your new, fledgling empire established and need to expand it or be exterminated.
