Some RV's come with 12 volt TV's wired to the house 12 volt system
Others come with inverters,, Some are small 300-600 watt, and power only the entainerment system(s) (usually only the main tv) Slightly larger ones (say 1KW) may power a few outlets or the remote TV) mine is 2KW, all the above plus the microwave.
IF your RV does not have one, one can be added.. A True Sine Wave inverter, installed, of reasonable size will be about a buck a watt, but, Well worth it. also.
INLINE type inverters such as my Prosine (No longer made which is why I'm so free with the model) act a bit like the electronics of a UPS, they charge the battery by shore power (or generator power) with a dang fine 3-stage converter in most cases, (I give it "Top band" rating, more on that in a bit) and instantly switch over if power is lost, TV does not even blink.
You need at least one pair of GC-2 Golf Car batteries or 12 volt equivalent per kilowatt.
The more I promised... (Top band converters)
3-stage plus at least one feature, or my prosine it is Temperature compensation, For my Intella-Power (progressive Dynamics) 9180 + wizard it is auto-equalization Which I personally like a bit more so that's the one I normally use.
Many RV's come with far less capable converters (Parallex 7300 for example is a single stage converter 7300T a two stage on a timer).
Hard to beat a top band converter (Oh and there are many in that band).
Home is where I park it!