Look, modders are like sand. Let me explain. I mean that as a compliment - they get everywhere, and often do it faster than you'd ever think. Take, for example, the modder who's already managed to unearth and unlock a developer mode in Baldur's Gate 3's brand new official modding tools, which could soon make custom levels a reality.
Yep, if you're counting, Patch 7 only came out last Thursday, bringing with it that long-awaited official mod support after a few months of beta testing, and we're already chatting about people going 'Sod the official stuff you're making it a lot easier for me to do Larian, I'm gonna try something properly difficult'.
The mod that unlocks the chance for folks to have a go at this complex stuff is 'BG3 Toolkit Unlocked' from modder Siegfre, who's previously had a go letting you have a LAN party in Skyrim by playing with your mates.