What size circuit breaker and outlet should be used if you want to plug in a 12amp. Deep freezer?

First, carefully review the manufacturers instructions...
They may list the recommended receptacle and circuit breaker size.

Otherwise, a 20 ampere circuit breaker and receptacle would be my
Choice. It's a bit beyond minimum but might last longer without issue.

AWG or wire size determines what size breaker you can use. 14 awg can handle 15 amps, 12 awg does 20 amps. Your freezer says 12 amps but when the compressor kicks in initially there will be a higher draw so I'd also go with a 20 amp if you already have 12 awg wire