The standard RV hookup cable is 30 amp 10-gauge 3-conducter (10/3 wire).
Even my old Coleman tent trailer had one. If the RV park hook-up is on a
30 amp breaker (which I think most of them are) then your trailer should
be set up to match that. Note: there are an increasing number of
50 amp hookups out there (for the big MoHo's and 5th wheel types)
A different topic is what power converter do you get, they come in
30a, 45a, 60a models, but those amps are at 12 volts-dc not 120 volts-ac.
The original uni-volt converter in my 65 safari 22' was a 20a unit,
I replaced it with a 45a model. These need to run the blower on your furnace,
lights, vent-fans, etc.