Could Caesar have conquered Parthia?

The problem never was to conquer it, but to keep it. Which with Roman technologies should be highly unlikely

If Trajan couldn't do it with the imperial armies of the empire's apex, then I doubt Caesar could do it at a time when Rome was a politically unstable republic on the verge of collapse.

Also bear in mind that Trajan invaded Parthia with much better intel and knowledge than the contemporaries of Antony and Caesar.

The fact that the Parthians had a sort of feudalistic, decentralized nature and traces of nomadic pragmatism was probably what saved them from being conquered by Rome.