Usually Paradox has some content DLC but the vast majority is cosmetic, so you don’t have to buy it but that money fuels their development of future content. Also with every content DLC they almost always release updates and extra content for free for the base game, I feel that Paradox is one of the only companies that do DLCs right.
Also they always allow mods, and a lot of their cosmetic DLCs can be immigrated by mods, so it’s not like they block people from doing what they want with their game just to shove cosmetics.