I would expect there to be bent valves as a minimum. Exactly how many and which ones will depend upon whereabouts in the four stroke cycle the engine was at the point of failure. The head will need to come off to be examined and reconditioned.

If your friend is extremely unlucky a valve may have punched through a piston crown. On some cars the sump can be removed and the piston/rod assembly removed with the engine still in the car.

A good garage should have an inspection camera and be able to look inside the chambers via the plug hole. It won't give an absolute diagnosis but should give a good indication of whether it's worth proceeding with head removal.