people who havent played original sin 2 shouldnt talk about what constitutes a sequal to it.
of all things that looked like it, id nominate the world design.

the combat? not very much.
This is probably not evident for those who havent played it, because they only looked at screenshots and dont know how the combat actually works.
but for one, you dont die this fast in OS2, there sno dicerolls, theres no shared initiative, theres no 3 actions like in DnD, theres action points like in XCOM, theres far more elemental reactions, theres no classes

The entire way the combat is structured is different. and since thats the main gameplay loop youd think that have to be pretty damn simmilar for it to be the same kind of game.