Fair warning, magic doesn’t scale well into the later levels. The way the game is programmed by default, your magic levels only change how much mana the various spells cost.

So for instance, as your Destruction skill increases, Destruction spells cost less. But the issue with this is that it doesn’t actually adjust your damage output; It only changes how frequently you can cast the spells. But this means later enemies start to feel extremely damage-spongey, as they have more HP and better defenses, so you’re having to throw more and more spells at them.

For other combat skills, your skill level increases the damage you do. But not the magic skills. There are mods to change that, but the vanilla experience isn’t great.