That's still a 12 year window with several motor and transmission options. Generally anything that's known to go wrong will look just fine until it does, so inspecting doesn't do a whole lot more than know it's currently okay. IMO the good things is old vehicles with low miles tend to make great values, you just have to be very patient in finding one. Try to find one that is low miles but shows steady use on carfax. Sitting doesn't do a vehicle any favors.
Hi and welcome!
The only really common thing on these is the front suspension wear. There are some years and models that are best to avoid. I would briefly say that for me, '03-'06 2.5T is best, with '06 being the best of those. I would say don't buy a '03-'06 T6 or a V8 older than '06. The '08 and up V8 are good, but really cramped engine bay and probably expensive to service due to that. '11 and up for the 3.2 is best. The 3.2 does have a really expensive accessory belt change at 10yr. 150k mi (actually less miles) . As far as I know, these are years and models that don't have specific known failure points; hopefully others will chime in on this.
It's a good idea to get an XC90 inspected at a good independent Volvo service, getting it scanned with VIDA/DiCE and hopefully having a good documented service history. If you share your location, maybe someone on here could recommend a shop. Any used car is a crap shoot, but there is no substitute for getting it up on a lift and inspected by a good mechanic.
Timing belt on 5 Cyl
Serp belt and tensioner on V8
inside door latches - the plastic breaks
Control arm bushings
sway bar end links
pads and rotors - rear wheel bearing get noisy
drivers door - ground wire wears out and actuator acts funky. Actuator is also a weak spot
heater blower motor. Multi thousand dollar job if dealer does it. very inexpensive if you remove all but one screw, snap off the motor, snap of the tab for one screw and mount it with one less screw
maintenance records - The ad for our 06 5 cyl with 137k when we sold it listed timing belt/water pump and PCV at 105k, rear wheel bearings, etc. I had a folder almost 2" thick with receipts. The second person to look at the car came with his wife and inlaws in a new XC90. The father in law had an 05 5 cyl, and he said he did everything I did to his car, so he knew mine was a good car. deal was done.