this is pretty common with DLCs for games that have proper ends...or even games that don't have proper ends. You can absolutely go do Dragonborn in Skyrim before ever tackling the main quest in any meaningful way, but that DLC came out years after the game released for instance. Sonic Fronters' The Final Horizon update is an alternate last fourth of the main game, requiring no game completion, and came out like a year after the game released. The only real major game I've played that released DLC that required main story completion because it continues the story is......the latest Pokemon games of all things.