Lay apple slices on a flat surface and sprinkle with cinnamon.
Arrange apple slices in air fryer, covering with a metal rack/trivet to keep the apples from flying around while cooking. Cook for 15 minutes, stopping to flip the apples every 5 minutes.
Once apple slices are drying out, turn temperature up to 330°F (165°C) and cook for another 8-12 minutes to crisp, flipping them halfway. (Remove browner chips as needed and continue cooking until all are crisped to your liking.)
Transfer to a bowl or plate to cool. (They’ll crisp up more as they cool!)
Serve and enjoy!
Store in an airtight container or sealed bag for 1 week at room temperature.