Only a commercial chest freezer will be adjustable and probably not high enough to be useful, so you have to add a controller. The controller monitors the temperature with a probe and turns the power on and off as needed. For a kegger, a single stage controller works fine.
Remember one unassailable statistic, as explained by the late, great George Carlin: "Just think of how stupid the average person is, and then realize half of them are even stupider!"
"I would like to die on Mars, just not on impact." Elon Musk