For another game, possibly. CK3, tho, probably impossible.
Paradox doesn't patch crusader kings unless they've got major issues to correct or change. Their checksum for Ironman/achievement eligibility is on a hair trigger as well, so anyone brave enough to invest their skills and a huge amount of time into modding for CK3 will have to study the patch notes in detail and compare the coding changes before/after as to how their mod interacts with the game to make sure it's even gonna work or not be redundant in some/every way.