Can I use dua.com without giving location permission?
Yes, you can. But other users' locations won't be precise due to the lack of information about yours.
When you register and create an account on dua.com, you are asked for a location permit. Location is required because, on dua.com, there is a feature called "Fly to a new location," where you can fly and meet people worldwide without moving from your couch.
To see how close you are to other users, and also to be on their radar and have a better match potential, you must enable location.