I bought a used 2001 Hyundai Santa Fe that has engine noise. I think it's loud, but the dealer calls it, "?

It is true that you will hear some lifter noise on some cars, especially if they have been sitting for a while. Drive it on a highway for 10 miles without the trans in 3rd gear, be careful not to over-rev the engine. If the lifters are able to pump back up, then this will do it. If they don't, then some may need to be replaced. This usually works. If not, what was the agreement on the purchase? Was a warranty implied?