That 500XPs (or whatever) in D&D took some calculus to get to. I think the expectation is to pre-build the encounters to suit the party. Factors include number of folks in the party(and their levels), number of monsters and CR levels…for starters. There’s even an Adventuring Day XP chart in the DMG!

Challenges are more narrative. Avoid detection by the castle guards, steal the dragon egg, sneak away into the night. 3 XP.

I should be clearer, XPs in D&D feels like a pacing tool. I don’t like that tool in my hands as the GM/DM. I want to hand it off to the players.