A "Starter Set" and an "Essential Kit"? Are you serious? How do these suggested numbers of players have anything to do with BG3?
This game is not a freaking tabletop game that actually involves 6 human beings. This is a video game in which things are processed by a computer. There is only you and your computer. It's a video game, so you don't have to worry about having too many people taking up room space and needing more chairs and tables and there being too much "socializing" and whatnot.
The Critical Role campaigns handle 7-8 players all the time.