There are a few different types of Nordic skis. I am guessing that you previously used Classical skis, where you ski with parallel skis in a track (or make your own trail). Those are the longest. For sizing classical skis, put your arm straight above your head. The tip of the ski should hit you right at your wrist. These have kick wax in the middle, under your boot to help you grab the snow and push off on each stride. (If you don’t want to deal with waxes, they have skis with fishscales in the kick zone, but they. are. so. slow.)
There are also Skate skis. They are shorter but you use a different technique, similar to rollerblading, your feet making a V. You’ll need a much wider area to move in. There is no kick wax on the skate skis, just a base wax on the whole ski for gliding.
You might also want to look at a back-country/touring ski. They are wider and shorter and meant for deeper snow where no one would have made a trail.
I would definitely go to a ski shop that specializes in cross country skis. They’ll be able to set you up with the right combination. They will make sure you have the right size poles as well. A shorter one for Classical and a longer one for Skate. I can’t remember how that sizing works, but they’ll know.
You picked a great outdoor winter activity and if you reallllly like it, you can get roller skis for summer training!