Had a look online today. S3 suspension is pretty basic for what it is, say comparing to multi-link suspension, so in theory should be easier to diagnose.
With all suspension related clunks, then start on the cheap side before you swap out major components.
As suggested, check the coil springs. With the state of the roads, not unusual to lose an inch on the end of the coi springl, either top or bottom. Wheel needs to be off to make a proper check, and you’re looking for sharp edges on the ends of the coil.
On a 2016 car, then shock absorber/strut isn’t a bad call, however, is it misting? Also look at the bump stops and their conditioning, it might be bottoming out?
ARB links, and ARB bushes would be next culprit.
That just leaves the top mount and the wishbone arm bushes.