I just tested this on my iPhone and location works just fine in airplane mode, even with WiFi off.
I wonder why. Mine doesn't work, it says location could not be determined. iPhone 7, iOS 12.4.
It's probably using GPS, which AFAIK is not affected by Airplane Mode (probably because it's passive?)
Android allows the user to turn location on in airplane mode.
Yes, I do this all the time when I'm hiking out backpacking. Without any cell or WiFi nearby I try to save battery by turning them off. When I want to check a location on my map I enable the location long enough to get a GPS fix and turn it off.