Unless you speak Arabic, or (maybe better) Urdu, you are looking at potential communication difficulties with taxi drivers. Goodwill in both directions can avoid problems. But as you are already talking rip offs, it's maybe best to steer clear of taxis and rely on ride-share aps which give more clarity in terms of fares and payment options, and (often but not always), attract drivers with language skills you might appreciate.

Note the Marriott is an airport hotel in name only. It's some distance away from RUH and offers paid pick-up and drop services rather than an airport shuttle.