Larian, voiced by Swen Vincke repeated in all interviews that the game will use the D&D Tabletop mechanics and combat with some adaptations to translate to a videogame (They usually refuse to compare with previous games but they always relate BG3 to the tabletop D&D)
"With respect to the combat system, this is based on D&D, so we’re using their combat system. We had to make a few tweaks"
Sc: https://www.pcgamesn.com/baldurs-gate-3/larian-developer-interview