Lies of P 's ending and final boss depend on various choices made throughout the course of the game. As a Soulslike, or rather a Bloodbornelike, Lies of P imitates much about the classic Dark Souls formula. Like many of the Soulslikes that came before it, Lies of P includes multiple endings, and has a regular final boss along with a "true" final boss, only unlocked in certain scenarios. What's unique about it, though, is a feature called the Lie System. Based on the 1883 Carlo Collodi novel The Adventures of Pinocchio, Lies of P repeatedly gives players the chance to tell the truth or lie at crucial moments in the story. Their responses determine the ending.

https://screenrant.com/lies-p-final-boss-multiple-endings-post-credits/