Yeah but I mean as just a something extra before the game over screen, something like the mid battle cutscene where they grow. No need to change the story just a small cutscene showing them win and maybe grow a bit more and then cut to the game over screen.
Sorry if it has been suggested already but have you thought about adding a bad ending cutscene to some of the main bosses like xaraziel if you lose to them? like a what if they won and maybe they get to grow and all that