This was the first result on Google

This reads like a shitpost. The math is eh, okay, but the explanations are totally wrong. I won't even try to figure out what "runs off watts" means.

Enough of any electricity source, using various converters can get any appliance working "technically speaking", but in the end the amount of energy available at the source and the rate of consumption at the end and any intermediates. So "technically" an AA battery can power an industrial electric press, but only for a fraction of a microsecond, using a lot of charge storing infrastructure and with a lot of changes to get the tiny bit of DC into the machine requires to operate, likely 3 phase AC power.

A proper explanation would say a lead-acid car battery provides power at around 12V and electric camping fridges nominally operate around 12V so you can connect them directly and operate it (so you can sorta say they both run off DC volts?). If not you would need a buck or boost converter. The available energy of the battery (Watt-hours is a useful unit here) and the consumption rate (in Watts) of the fridge determine how long you can use it on the battery.