Wash and dry the apples. Core them, then slice into 1/8-inch rounds using a mandoline for even thickness.
Stir the lemon juice into the cold water. Soak the slices for 5 minutes, then drain and pat completely dry on a clean towel.
Toss the dry slices with the cinnamon in a large bowl until lightly coated.
Arrange the slices in a single layer in the air fryer basket or on the racks, without overlapping.
Set the air fryer to 135°F (or the dehydrate setting) and run for 4 hours, flipping or rotating the slices every 90 minutes.
Begin checking for doneness at 4 hours. Cool a test slice for one minute — chewy apples should be leathery with no visible moisture when torn; crisp chips should snap. Continue in 30-minute increments as needed, up to 6 hours.
Transfer to a wire rack and cool completely, at least 1 hour.
Pack loosely into a glass jar and condition on the counter for 7 days, shaking daily. If condensation appears, dry the batch further before sealing for storage.