Ok I've been thinking,
BG4 Spelljammer adventure fighting the Gith civil war overspilling into the realms. We thought
would save the world, instead it has us caught in the crossfire of a planar conflict! Only YOU can put a stop to this conflict before not only Toril but all worlds are consumed in dragonfire!
BG5 Go off with Withers to fight the dead three as part of withers plan to restore his power teased in the credits scene, you saved the world, you taken down a false god and an ascending god, now your ol buddy withers wants you take down the three!
BG6 whole unrelated adventure, PC, and low-level adventure module story. Maybe to Warlock's Crypt ?
