Add endgame "infinite" content (player, gear and difficulty level)

Add an endgame mode that allows the player to play "forever", levelling up their character, gear and build in an infinite dungeon crawling mode, or even using the open world for quests like world event and boss raids

A way to implement this would be making so the save has 2 "versions", the storymode version that goes to the games normal player and gear cap, and an endless mode where the player can level up forever and get better and better gear.

an example i made was using the dungeon system, so that the player goes inside a dungeon that is paired with their level, and they not only level up from normal gameplay loop(going past level 100) but get higher than 150 level gear after completing it, allowing them to play forever or stop at the desired level they want.