The crockpot should work fine while plugged into 20amp. Of course it depends on whatever else you are running at the time. There's a max limit of what all you can run on 20amp simultaneously.
I looked on the bottom of my crockpot, the label read it's only 120 watts.
A toaster is about 1250 watts, to give you a comparison.
Microwaves are 900-1500 watts
A coffeemaker 600-1200 watts.
Laptop computer 50-75 watts.
For example 120 watts/110 volts = 1.09 amps
1000 watts/110 volts=9.09 amps
2200 watts/110 volts= 20 amps
I have spent time with only 20amp electricity. You have to be careful to keep everything unplugged, except what you are using. Some appliances can't be run together, it will trip the breaker. Like trying to run the 1000 watt microwave and 1500 watt ceramic heater simultaneously, won't work, so you unplug the heater, use the microwave, then plug the heater back in. Sometimes you seem fine, then your battery charger kicks in, and BAM you trip the breaker. I think battery chargers are around 50watts.