A bit of an odd question, perhaps.

But I have been thinking about it for a magic focused character of me, that she might want to use magic to increase her lifespan and her youth. I looked around for lore, to see if this has been mentioned before. But I could not find anything myself. It seems fairly logical to me, as mystical sources such as magicka is likely able to affect the body and even the soul of a person, should he or she put alot of time in it.

But, I don't like making things up, who knows I might be wrong.

What do you think?

If the person is an extremely talented mage in restoration, yes, he / she can, the arch mage in the college said something along the lines of " What you learn here will last you a lifetime, Several if you are talented " Also, the process of "aging" is just what happens when more cells die than are created, so through restoration, if one is talented, one could control the cycle and control the aging process as well. I mean, restoration is the mastery of life forces.

I don't know about that, but many use it to extend lifespans.

Well Divayth Fyr is over 4000 years old so I think that is possible

It's almost certainly possible. The Telvanni Wizard-Lords live far longer than regular Dunmer do, and Janus Hassildor is able to get away with not aging (actually due to being a vampire) with the fact that he's supposedly a master sorcerer. And as Savos Aren, Arch-Mage of the College of Winterhold says, "What you learn here will last a lifetime. Several, if you're talented."

Hmmm, I wonder what my Necrowarrior could do then.

She is able to do Conjuration and frost Destruction. But she isn't corrupted by her Dark magic, as she is good moraled.

I think she could delay aging aswell. If not, I think I'll find a reason, eventually she will be Arch Mage of the college, so that gives more possibilities.

Yes, though I think it has more to do with necromancy than restoration (but it's up for debate), if I remember right from morrowind.

The telvanni regularly extend their lifespan indefinitely (depending on skill I guess), a good example would be Neloth from dragonborn, he was already an ancient wizard-lord in morrowind's time, 200 or so years later he looks even younger than he did back then.

I wouldn't be surprised if other magic organizations would do the same.

In short: Yes. Necromancy and restoration being the most common.

Illusion also deserves an honorary mention.

Yes magic delays the ageing process. Fyr and Neloth are both millennia old wizards, while most of their race lives to be a few centuries old. How long you can delay it is mostly dependent on your skill level and how much you use it. Sotha Sil was apparently several centuries old before he became a god. So magic can be used as a fountain of youth so to speak.

Dunmer Telvanni, Altmer, Maormer, and possibly sload are proof magic can expand one's age and stop the aging process.

"What you learn here will last you a lifetime. Several, if you're talented."

We don't really have much information on how long sload live without magic so I don't really think that one counts. The rest are good examples though.