Just like in the first Hades game, beating the final boss in Hades 2 doesn't mean the game is over, not even close. The first time you beat Chronos, which granted, is going to take a while probably, you'll grab his resource (Zodiac Sand) and head into Zag's room only for the game to tell you this is the end of the early access progression at the moment and kick Melinoe back to the Crossroads.