Original Sin are just spin-offs in the end.
The main line is Divine Divinity -> Divinity 2: Ego Draconis/Flames of Vengeance -> Divinity 3?
Beyond Divinity never happened.
Feels great in these Gothic-likes to finally become powerful and then revisit places on the map to clean house.
But the most enjoyable is really to be able to pick up whatever you want without having to worry about getting encumbered.