The following assumes you buy an out-of warranty Duc:
Adding a warranty is not likely worth its cost to you, even IF you could find one, because it'd be "aftermarket" and those are notorious for being rip-offs. Just thoroughly vet a used bike, demand service records, have it inspected by a Ducati shop prior to commitment to buy, and get roadside assist.
Do a deep dive in the Multi forums here to know what issues to look for before u buy. Happy hunting. The Multi guys here seem to love their bikes... just get em started. Don't say I didn't warn you