My RV uses a 30 amp plug to access the electrical power. I'm use to plugging into 50 amps with adaptors. Can I do the same with a 20 amp socket? And what should I be aware of when using a lessor source?

You need to stick with a 30 amp or larger plug. "And what should I be aware of when using a lessor source" well to start with fire, death, tec...

They do make adapters to plug in a 30A/120V travel trailer plug into a 15 or 20A standard receptacle.
They are not a fire hazard because if you draw too much the breaker will trip.

Just do a Google search.