There are too many variables to give you a definitive answer.

Get the car high enough up in the air to get the wheel(s) off, and take some pictures of what’s in there. Could be aftermarket, could be stock. If aftermarket, you’re likely to see adjustable collars to raise and lower the spring perches.

The OEM suspension on a non-ACR car shouldn’t ride like you describe IMO. Mine was best described as bouncy, kinda like a pogo stick, but not harsh. It is also not adjustable, so you get what you get.

If the car is an ACR (or has the ACR shocks/springs), I’d fully expect it to be harsh. That’s due to the extra spring rate required to compensate for the downforce of the wing at speed. It is also adjustable (ride height, compression and rebound if I’m not mistaken).

Bottom line: take some pictures, and post them up so we can see what he is working with. Could be a blown shock or two, or it could be poorly chosen aftermarket components (e.g. spring rates too high).