What do you get from leveling up?

Question, what do you actually get from leveling up. It’s not really clear. I’m mainly asking because I wanted to go back to a skipped difficult fight when I was a higher level but it didn’t seem easier.

Also is there level scaling of enemy?

There is no level scaling. You get mutation points for leveling up, thats it. (and you need them)

Alright good to know thanks.