It isn't a clone. Is it going to be similar? Of course; it's Larian. Should it be similar? Of course. They produced the massively successful and highly lauded game. Turn based and the ability the interact with your environment are crucial elements that resonate with D&D. In that way DOS was more D&D than BG ever was.
Not only that but the combat mechanics is not the same as DOS, BG3 uses a completely different mechanic,it used 5th edition rules which DOS2 didn't use . And story/lore wise it's different and the monsters too. So it's far from a clone.
