Also, there are easy solutions that take zero intellectual rigor:
1) No party size limit, balance the game for full parties and let players live with the consequences if they don't want a full party. 2) No party size limit, combat difficulty and skill check difficulty scale with party size. 3) Party size limit based in some way on Charisma or a similar stat. 4) Just don't have more companions than you want people to play with! If you really think good adventures only happen when you have a group of four people, then just don't have me meet more than four people! And don't tell me that limits player choice, because you're already limiting player choice by insisting that I only have three companions.
Too obvious and too easy.
You can't have a party size of greater than four people but you can turn your camp into a menagerie. You wont get a larger party size because that would require writing a lot of extra 'romance' options and there's nothing more needed by a group of badass adventurers who are out to save the world than a nice romance. Well, except maybe coloured horns and pronouns.
I'm currently running a party of 6 with this mod: Recruit any NPC - Transform NPC Into Playable Character - Make Full Custom Character Party - No party limit - Resurrect Dead https://www.nexusmods.com/baldursgate3/mods/1646
I use other mods so the combat is not a breeze (e.g. no 5 attacks per round for me). My level is about where a party of 4 would be - I hit L9 in the fight at Moonrise gates (or maybe in the building somewhere).
