It isn't as hard or problematic as most think to make an easier mode that is after the game is finished.
Like in Nioh they could have made it that when you die you don't lose anything you collected option, so you'll be getting stronger continuously, also yes you can make it a lot easier with bosses dying with less hits and you tanking more.
duduspace11 "Well, since we are estimating costs, Pokemon Red/Blue did cost Nintendo about $50m to make back in 1996"
Mr Puggsly: "Hehe, I said good profit. You said big profit. Frankly, not losing money is what I meant by good. Don't get hung up on semantics"
Azzanation: "PS5 wouldn't sold out at launch without scalpers."