Depending on how it was calculated it might be far less impressive than it sounds.
The number of possible permutations increases very fast with the number of decisions. Even old games like Fallout 1 and 2 probably had several thousand possible ending combinations.
If the game has even 10 main endings(and it very likely will) that's still more main endings before permutations than anything that's been done before. It it has 20+ main endings before smaller permutations that's way more than most people will even know what to do with. And they are going full on D&D do whatever you want sort of approach here so yeah, there will be a lot there. When Larian say they don't know how many core endings there are, that almost certainly doesn't mean five...we're most likely easily looking at over a dozen.
