Short version:
not as a DIY job, no. The belt inside the Brose 2.2 (your Gen 3 Levo motor) is buried in the gearbox, and Specialized don't sell it as a serviceable part to owners. It's a dealer/service-centre job — and in practice that usually means the whole motor coming out and either a belt swap on the bench or a full replacement unit.
Here's the lay of the land:
It's a known weak spot. The Brose belt on these has a reputation.
Tthibault16 reported a failure at just 700km, and
singletrackminded put the out-of-warranty cost at around $780 for motor plus labour. So you're not imagining it if yours is making belt-ish noises.
Warranty first. Gen 3 motors carry the standard 2-year warranty. If you're inside that, this is Specialized's problem, not yours — get it booked in. The good news from the community: dealer support on these is generally solid.
westcoastmtbr noted that even with the ageing belt issues, local dealers tend to be generous with warranty and quick on turnaround.
Out of warranty? You've got an "assisted purchase" scheme through Specialized that knocks the cost of a replacement down, so it's worth asking your dealer to quote that route as well as a straight repair. Some workshops will do a belt-only fix rather than a full motor swap, which is cheaper — but it's not something Specialized officially hand owners a parts kit for.
So the honest answer: you
can get the belt replaced, but it goes through a dealer or a competent independent who's happy to crack the motor open — not over the kitchen bench with a 4mm Allen key on a wet Sunday.
One thing worth knowing if you ever upgrade: the Gen 4 Brose motor dropped the belt entirely, confirmed by
fankus via a Spesh service centre. So the problem genuinely went away on the newer platform.
If you can tell me whether it's actually failed, or making noise, or you're just planning ahead — and whether you're in or out of warranty — I can point you at the most sensible next step.