Modern cars are user unfriendly. I would pay extra for old fashioned mechanical dials.
Here are your options. First, if you don't want air circulation, set the controls to recirculation (dedicated button), and then hit the Off button (also dedicated). It is my understanding that recirculation may cancel after a certain length of time because Koreans apparently believe fresh air is important to health. It will certainly reset after you turn the car off. As best I can tell, if you have set recirc and turned off HVAC, there is zero air circulation (previous cars I've had were leaky set this way at highway speed). You can also turn off the dash vents with the dial next to them. That way you can have circulation, but no air directed at you.
Next, if you do want unconditioned air flowing into the car, you must set the temperature to (about) the ambient air temperature (weren't old cars with red to blue dials easier?) displayed on your dash. Only then will the temperature not be adjusted.
One other quirk is that under some conditions, the auto defog system will turn on your AC without the AC light coming on to help dehumidify your interior space (specifically the windshield). If you don't like that, you can defeat it by pressing and holding the front "defrost" button. It has been over a year since I have done that, but as best I recall you will have then have an option to turn it off on the touchscreen. This option stays "sticky". Every time you turn the HVAC on thereafter, you will see a message on the top of the touchscreen informing you that ADS is off. Even with it off, you can certainly turn the AC on should you need it to defog your windshield. It may well be that if the AC is on with ADS working, heat will also come on so your interior temperature remains at the set temperature - not sure since I keep ADS off. But if that sounds like how you want it to operate, you will have to turn it back on.
It is all very complicated. Having this question come up again and again only demonstrates how far removed from user friendly interfaces car makers are. They are competing with the other car makers of course, and if you cannot set a "thermostat" in your car like your home, it won't seem like a modern system in the sales lot. I thought it was wild how perhaps forty years ago similar systems became available in luxury cars and thought at the time it was stupid. Quite sorry that they've finally trickled down to economy cars - I think in the last ten years. I can sort of understand the luxury frame of mind, set your temperature and never touch the controls again. But cars are not like homes, direct sunlight or shade totally screws things up and a simple dial makes it easy to find comfort when needed. I much prefer manual control.
2018 Kia LX HEV Metal Stream with Advanced Tech