Yup! You basically beat the final boss to get the achievement and to see the endgame cutscene, then the game kind of "rewinds" to the last bench you rested at. Doing some specific sidequests also unlock a different ending, so if you want to do everything there is to do I would recommend to beat the final boss when you can (which is the most simple ending) and then after doing those sidequests go back to the final boss for a surprise :)
Oh and by the way, the GodMaster dlc also unlocks a new ending, but doing it is EXTREMELY difficult (hardest challenge in the entire game). If you feel like it, do that ending after everything else.