When you the car set to Auto, all you can do is select a temperature. The car then decides how to adjust the fan speed, heat/AC on or off, vent mode, and recirc mode, to achieve that desired temperature. Typically if you are trying to rapidly cool down the interior of a car, you want recirc on. If it’s cold out and you have fogging you want recirc off, but AC on (using the AC helps dehumidify the interior).
The temperature setting is active all the time. Set a fan speed of 4, set the vent mode to the dash mounted ones, and turn on the AC/heat and then slowly adjust the temp up,and down and there should be a change in the temp coming out of the vents. Try cranking it all the way to low for a bit, and then all the up to high and it should be readily obvious it is working with Auto off.
For me, I leave it in Auto most of the time, and adjust the temp up and down to get the desired air flow, which is usually a gentle breeze on my face. Occasionally if it is cold out, I raise the temp so the cabin gets warm, and then adjust the temp back down to a comfortable temp.
Some owners have reported having a problem with their Bolt blasting hot air when they had the temp set to 73 or 74, and the outside temp being above 80 or so. I believe it required multiple trips to the dealer to get it properly diagnosed and fixed. Something to do with a faulty sensor.