You always need a reason to declare war in Crusader Kings 3, but all sorts of reasons ... With or without the "Royal Court" DLC, your ruler can get items that increase their monthly Piety income.

Crusader Kings 3 was originally released for PC in 2020 ... Since then, the grand strategy game had multiple expansions, such as “Royal Court” in 2022, “Tours and Tournaments” in 2023 ...