Look for a controll panel on the fridge. It might be outside under the fridge vents. Or on the front. I've really never seen a fridge that was just 12 volts in a camper. As stated it will drin the battery fast. Plus they dont cool very well on 12 volts. More then likely you have a 3 way fridge.
2012 kz spree 220 ks
2020 Silverado 2500
Equalizer ( because i have it)
Formerly a pup owner.