Can the Xterra be lifted?

Yes, absolutely. Solutions range from $60 for a pair of 2" shackles and a free tweak of your stock torsion bars all the way up to $1500 or more. The more lift you want, the more it will cost, generally also varied by the quality and source of the components. Check the various vendors mentioned here for their product offerings.

The Xterra can be lifted up to six inches by using both 3" body and 3" suspension lift kits. Tires also add lift (new diameter minus old diameter divided by two).

Body lifts are generally used to give clearance for larger tires alone whereas suspension lifts are often used to also gain wheel travel or "droop."