In ours 5th wheel Cougar, the amplifier is in the bedroom right behind the wall plate with the antenna connection/12 volt plug/LED and button. Removing the wall plate, you can pull out the amplifier and see it is in the line. Some of the newer Winegard plates and amplifiers have it all integrated into just the plate, but I would assume not most, but not sure.
The amplifier included with our RV is a very small, limited little amplifier. Over the years, we've had several different RVs, and each one has had varying success at our favorite camping spot for TV reception. On our current 5ver we have poor reception, so I upgraded the Winegard Sensar to a JACK antenna, after seeing positive reviews, and .... wait for it .... It didn't matter.
If we're staying anywhere for a few days, I pull out a homemade antenna, and a better amplifier and connect through the external antenna coax. I go from probably 2 weak channels to 15+ channels using the homemade version.