What would a Duke do in a fantasy setting?

This world is quite modern and is a lot like Earth, the only difference is magic and the how the social hierarchy works.

In this world, people of nobility have more power and more responsibilities, such as being in charge of using their unique powers to make sure specific power stones don’t go extinct by pouring their energy onto caves that creates power stones over time and then distributing these stones.

Technology is pretty behind compared to Earth, but that’s because they mostly rely on magic to for almost everything so everything there still feels pretty modern. Magic is advancing at a rapid rate to the point where some technology is not very necessary unless it’s something magic can’t replace just yet.

That’s why, I’m wondering what a Duke in my story would do for their duties. ⬇️

The Duke in my story does a lot of paperwork and occasionally holds small meetings in his study, he stays in his study most of the time throughout the day, more important meetings are held elsewhere, and his words do impact law, but I don’t know exactly what he would even do in those meetings and to what extent he should affect the law or what else he can do for his duties. I also don’t know any of this would feel believable in a fantasy setting.

Please help!