The way I see it there are two general categories of "sequels", (meaning a game that shares a name with previous titles but with a +1 numerical in the title).

It can be a story sequel and in that case the story is what matters. This will not be possible to properly judge untill we know what the story is so not untill release.

The second way a game can be a sequel is to have similar but still further developed mechanics. This would be a kind of weird goal when following up on 20 year old games. I think BG3 visualized as a modern rpg is a better idea than BG3 visualized as a retro game.