Even once players have beaten the main story of Bayonetta Origins: Cereza and the Lost Demon, the true final boss remains a final challenge to unlock by accessing an additional chapter at the end of the game. Named The Affirmer of Phenomena, this fight earns players a secret ending that lends new context to the story. In addition, several new outfits are gained once this foe is defeated, allowing players to go through each chapter with a new gameplay style that changes their experience from the first playthrough.
https://screenrant.com/how-to-unlock-true-final-boss-bayonetta-origins/