I have a 2012 Colorado 4x4 that’s overheating but no warning lights to let me know it’s boiling and overheating

I'm going to assume that when you say "overheating" you are experiencing coolant and/or steam leaking out from under the hood.

If that's the case, then the first thing to check is where the leak is coming from.

BE VERY CAREFUL WITH THIS AS THE LEAKING FLUID OR STEAM IS VERY HOT!! For ALL the steps below, WAIT UNTIL THE ENGINE HAS COOLED!

If it's leaking from a hose or connection, replace or tighten that. If it's leaking from the radiator, replace that. If it's the water pump, replace that.

The most likely scenario, however, is the pressure cap. Check that it's properly installed. If it is, then remove it and replace it with a new one.

Most auto cooling systems are designed to operate under pressure, usually 10-15 psi above ambient. That has the net effect of raising the boiling point of the coolant. If the pressure can't build due to a leak, then the coolant will boil at a temperature that is lower than normal operating temperature and you will appear to have overheated but the temperature gauge will read "normal".