What are you trying to do with the vehicle? Regardless, big tires would be relatively low on my initial to-do list for a 21 year old vehicle for a kid.
What are your current gear ratios? With the stock 5-speed (~3.8:1 first gear, right?), I'd be very cautious about over-tiring the vehicle without correcting the gearing...unless you like to replace clutches all the time.
What would I suggest? Here's the plan:
First $1000 - fix what's wrong or questionable. Fluids, all u-joints, front wheel unitbearings, brakes, steering joints, ball joints, motor/trans mounts, axle seals, etc. No AutoZone crap, only good Spicer/FederalMogul/Moog parts. Upgrade headlamps (Hella e-Code lamps have been good to me). Not exciting or flashy, I know, but essential. Teach the kid how to lube and inspect steering and driveline.
Next, make sure springs and shocks are right - Cherokee springs like to sag, particularly the rear leaves, which always appear to be saggy. Freshen up or replace as necessary. A rear add-a-leaf might solve things. A front swaybar disconnect might be worthwhile.
Then, a set of good 30x9.50 tires (A/T or M/T based on intended use) + a full-size spare. I think these will clear without too much trimming or lifting. Throw in a good recovery kit, first aid kit, and emergency gear.
Let the kid drive and explore, without worrying that the flashy stuff detracted from the essential preventative maintenance. Big tires and a flexy lift won't seem very exciting while waiting in the rain for a tow on the side of the road. If bona fide needs evolve and additional modifications are necessary, they can be addressed as necessary.