A lot of good suggestions in here.
Personally I'd second Earthdawn.
It was beautifully worked into the world and was something you could discuss in-game without going meta. Even things like levels were in-game magical terms.
I don't know why, but relatively few RPGs bother to do this in any real way. It's mystifying, really. Any RPG could match their world and their magic system, could make their system use terminology and concepts that the characters could use. It's not even hard to do. But the vast majority of magic systems are almost extrinsic to their settings - that very much includes D&D and most variants. Some settings make varying levels of effort to try and make D&D magic not extrinsic, but partly because D&D has been through so many editions, and the settings persist, this isn't very effective. And it's kind of sad, because when the fiction and mechanics align really well, you get something incredibly special. Something many generally-good RPGs don't have!
It's something that still happens to - the magic system seems bolted on to a game, rather than truly being part of the game and setting. Some others are in a middle-ground, where it's partially worked-in, but not really.
Importantly with Earthdawn too, all the adventurers used the magic, which lifted the idiotic burden of "martial vs magic" which D&D and many others have chosen to nigh-eternally torture themselves with, usually achieving nothing but damaging their suspension of disbelief and playability.
And by making it part of the world, you think of stuff, or easy uses for magic, of obvious human things, that most games just neglect because their magic is all about combat or summoning or violence - even though in human history and the imagination magic tends not to be about those things.