One Baldur's Gate 3 modder managed to implement real-time combat like the classic games, but you should probably wait for them to figure out a pause button before diving in
Baldur's Gate 3 modder tinybike has taken the first steps toward making a version of the game with the original series' real time with pause combat—instead of everyone taking turns, the action is constantly moving, but you can pause at any time to issue commands. Right now the WIP mod only has the "real time" and lacks the "pause," but it's already an impressive transformation of Baldur's Gate 3.
I have to level with you though: I think real time with pause combat was a disaster for the human spirit and our collective progress. Or at least a disaster for RPGs. Ok, maybe I do enjoy a lot of RTWP games, but I'd still rather have something fully turn-based or actionized, not this weird middle ground where my party members always seem to ignore my commands or let their pathfinding take them on a circumnavigation of the globe to reach an enemy, and I don't notice until it's too late because everything's popping off at once. That said, I really respect tinybike's vision and technical execution on this thing.
The modder describes their work as a "very very very rough draft" and has a demo video showing it off on YouTube. In the video, tinybike delves into the coastal ruins near the Nautiloid crash in Act 1, fighting the bandits inside in real time, with multiple enemies moving and acting simultaneously. Notably, tinybike is flying solo here. Alongside working out a pause feature, implementing party AI for the characters you're not actively controlling will be an important part of a more complete version of the mod. I'm also curious as to whether this mod might work in multiplayer eventually.
Still, if you're one of those sickos who swears by real time with pause, there's a light at the end of the tunnel for you with Baldur's Gate 3. You can follow tinybike on YouTube for updates to their progress, and they've also uploaded the prototype version of the mod to github—but trying to play BG3 all the way through in its current state would be one hell of a challenge run.