The typical 6 prong trailer plug usually has a power side to it. The 4 prong plugs do not. However even on heavy duty trucks the power side on the trailer plug typically has a low amp rating and isn’t very good for heavy RV charging. Trickle charge yes it’s possible. Fir heavy charging most people rely on the trailer be it generator, solar or utility hook up.
On my small camp trailer all our needs are easily covered by a simple solar charging system. $30 solar controller, and whatever wattage panels you need anc your set for basics, fridge, lighting and small devices etc.
AC or AC/ electric heat pump you need a heavy generator or utility hook up. No car will power those.