Depends on how much you like reading event dialogue.
The fun in Stellaris, at least for me, came from the bajillions of sci-fi references and events. The downside is that a lot of those come from DLC. The base is good by itself though, and you can always “acquire” the add-ons through other means.
Nah CK3 changed some things but the base gameplay is fundamentally the same. If you had a working knowledge of CBs and inheritance you’re already halfway done.