It seems that you can do a thousand playthroughs and it still wont be enough. One player, named Mysterious_Ad_1525 on Reddit, posted that they had spent almost two thousand hours playing Baldurs Gate 3. They continue saying that even all this time, they are still discovering new lines of dialogue, namely some concerning Karlach and Illithid Tadpoles.
Source: N4G PC Even After Thousands of Hours, Baldurs Gate 3 Fans Are Still Discovering New Dialogue Options