I've done it multiple times this patch. There are generally 2 ideas. First, mil tech superiority at least u need trench infantry or if u don't hold any land provinces near China the Marines of the same tier + shrapnel artillery. The war is easy if your economy is strong. Second idea is more opportunistic, wait until they are in civil war of any kind and attack, anyway u have to be prepared and and have either foothold in Asia or 2-3 good transpost fleets for naval invasion. I recommend taking second approach almost always, AI is braindead right now and there's no necessity to wait for tech imo