Sextants aren't really made for use on land, you need a very flat horizon to use one, you can use an "artificial horizon" but you'll loose some accuracy. A sextant is made for observations at sea, where a ship would be bobbing up and down. On steady land, it's much easier to just measure the angle a star makes with a level base. I'm not sure of the exact name, I've seen old telescopes with a protractor on the side, and a level and compass on the base.

But, so long as it's just for fun, you can rely on your phone for updated star information and time.