[quickthrowman]

Yes, but only for circuits with multiple outlets, an individual branch circuit must use a wiring device not less than the ampacity of the branch circuit.

You are allowed to use 40A and 50A receptacles on a multi-outlet 40A circuit. You’re also allowed to use 15A and 20A receptacles on a multi-outlet 20A circuit.

Table 210.21(B)(3) of the NEC

https://up.codes/s/outlet-devices

[Kirby64]

You have it backwards. If you have a single receptacle on a branch circuit then the OCPD (breaker) must be sized at or under the receptacle. I.e., a 50 amp outlet can be backed with a 50 amp breaker or anything smaller. You could even have a 20 amp breaker (and 12 gauge wire) backing a 50 amp outlet, which is common for welding applications where peak currents are extremely high on arc start but continously are much lower. There's a specific carve out for welders as well, but it applies to any outlet.