Dice the apples into small, even pieces and add them to an air-fryer-safe baking dish or container.
Add the brown sugar, cinnamon, and lemon juice. Mix until the apples are evenly coated.
In a separate bowl, combine the flour, oats, brown sugar, and cinnamon. Add the cold cubed butter and use your hands to mix until the mixture becomes crumbly and resembles coarse crumbs.
Evenly sprinkle the crumble topping over the apple filling.
Air fry at 350°F for 15–18 minutes, or until the apples are tender and the topping is golden brown.
Let cool for a few minutes before serving.