what size tires can you put on that?
You still need to hear the year and details from the seller, but I have a bit of information.
The photos show the wheels are held by QR skewers, and the paint also suggests it is a pre-2021 model. I think Q45s before 2021 have 26" rims.
I have a 2021 Q45, and I had an early Q I got from JT. The 2021 model comes with 650b rims which accept up to 1.75" tires. I have replaced my wheels with 26" rims, and I have 2.0" tires - which work out to almost the same diameter (so no gearing changes).
The early Q with 26" rims also fit 2.0" tires without issue. This was one of my buying criteria - I want 'balloon' tires for mixed surfaces, comfort, and low rolling resistance.
I don't have the early Q now. I think the 2021 Q45 might handle 2.13" tires on 26" rims - but the 2.0" is certain.