GPS actually doesn’t have to rely on a wifi connection, and you can use it in Airplane mode because it doesnt transmit anything. If you have a window seat you can often get a GPS fix just with signals through the window. It can help if you have an app on your phone that shows you what GPS satellites you can see, it will tell you when you have a good fix.

Then, just open your maps app of choice, and it should still know where you are. You won’t get a detailed map without an internet connection, but if you zoom out enough you should be able to see what part of the world you are in.