If you want a near perfect recreation, then play through Solasta to get an understanding of the mechanics. They have a lesser license than Larian so they often have to make nearly identical "Homebrew names", but its amazingly faithful.
This. If you want to acquaint yourself to 5e rules, and isn't interested in going through the books or playing a tabletop session, Solasta is your best bet.
Problem is, it won't be particularly relevant to BG3, for reasons mentioned above.
