DIAGNOSIS: That's almost certainly the drum support rollers wearing out. They're plastic wheels with a rubber tire, and when the rubber degrades or the bearings wear, they thump loudly with each rotation.
FIX: You'll need to replace the rollers. It's a known wear item. To check, unplug the dryer, remove the front panel (a few screws along the top edge and inside the door opening), and you can see the rear rollers. Spin them by hand. If they don't spin smoothly or the rubber is cracked/gone, that's your culprit. You can get a replacement kit with multiple rollers and the matching glides.
IF THAT DIDN'T WORK: While you have it open, check the felt drum seal around the front opening. If it's torn or missing chunks, the metal drum can rub against the front bulkhead, creating a different scraping/thumping sound.
HEADS UP: When replacing rollers, don't overtighten the center mounting screw. It should be snug, but if you crank it, you'll crush the plastic hub and the roller won't spin. Just get it tight enough that it doesn't wiggle.