Welcome, and good luck in your search! Aside from the usual - noises/smells/acceleration/deceleration/handling issues? Look at the Carfax, make sure any/all recalls (including Fuel Pump Control Module) are complete, and familiarize yourself with relevant TSBs before going into the deal. Mostly take off the appearance cover, note for signs of dirt accumulation near hose clamps (possibly cracked/loose/leaking oil or boost).
CPO doesn't mean it will be perfect, just that it has passed THEIR points of inspection. CPO isn't really B2B either, so know what is included what isn't. Even if it all "looks" good, you will want to do normal maintenance checks like air filter, cabin air filter, oil & filter change etc at a minimum. You will still want to get it up on a lift, take the belly covers off, etc. right after you buy it, to really make sure there are no issues with it. Check the struts and shocks for dampness, shouldn't be an issue with this mileage, but you never know. Verify underbody and exhaust system integrity.
If you really want to be proactive, you will want to have all fluids exchanged so you have a known starting point. Definitely have the PTU/RDU fluids serviced, whether at the dealership or an independent repair shop/trans service shop. Change the spark plugs, Motorcraft SP534 will work just fine. May want to keep spark plug boots on hand in case the ones on there are reluctant to come out.