Hey @SamMills1994 welcome to the Middle East! Off-road desert driving is one of the best experiences you can do in this region, perfect for the car enthusiast, shutterbug, social gatherings, Adrenalin junkie, or even time away from work.
So I Don’t drive an Xterra so @Krishna R, @M.Seidam, @Rizwanm2 @Chaitanya D might be some of the people that might be more qualified in answering your question.
however in my opinion if it’s in your budget a new car is a much better option especially if your planning to off-road. Only reason for this is because used off-road cars could have a list of issues you aren’t aware of, especially the chance of a bunch of third party modifications which you don’t need to enjoy the deserts of the UAE, this way you avoid the need of thoroughly checking and testing cars from previous owners, and you can get warranty for certain dealerships.
Besides those minor inconveniences you can go ahead and check out used Xterra’s there is a bunch on the market if you look at carswitch or dubizzle even the Facebook marketplace might be a place to check, you’ll notice used cars will have a better price but don’t let them fool you, especially when buying from Sharjah, another big tip is to always check the VIN number of used cars this way you can see if it’s been in a accident in the past and determine if the previous accident is worth it for the integrity of the vehicle