Larian Studios Forums Baldur's Gate III Baldur's Gate III - Mega-threads and Guides Party Size Discussion

You're not alone.

https://forums.larian.com/ubbthreads.php?ubb=showflat&Number=679595&page=1

I already tried the game with a party of 5 and 6 and it's way more fun.
More things to do during combats, more action point/round, faster combats more synergies between characters, more interactions, more variety,...

The only con- is that the game is even more easy but with a better balance and less OP mechanics, it could be amazing.