There are some games that just are the expansions like any LCG. I’m most familiar with Arkham Horror. The base game is basically a tutorial and you have to buy into some campaign scenario to get the full experience. That feels like a different category of thing entirely though.
Council of Verona - the original version had a poison expansion. My understanding is more recent editions include the position expansion in the base game because it quickly became accepted as never to truly play the game.
Feast for Odin - there are some game strategies that are just better than others in the base game so some action spaces almost never get used. The Norwegians expansion added things to beef up the underdeveloped strategies and a new action board where every space feels more viable.