Dry the drumsticks: Pat the drumsticks very dry with paper towels, getting into the folds of the skin. Dry skin is what lets the air fryer crisp it instead of steaming it soft.
Mix and coat: Toss the drumsticks with the olive oil. In a small bowl, stir together the baking powder, paprika, salt, garlic powder, onion powder, brown sugar, pepper, and cayenne if using, then sprinkle it all over the drumsticks and rub it in to coat evenly.
Preheat the air fryer: Preheat your basket air fryer to 400°F for 3 to 5 minutes.
Air fry the first side: Arrange the drumsticks in a single layer with space between them, working in batches if needed. Air fry at 400°F for 10 minutes.
Flip and finish: Flip the drumsticks and air fry for another 10 to 12 minutes, until the skin is deep golden and crisp and the meat reaches at least 165°F at the bone, ideally 175°F for dark meat that pulls away clean. Air fryer models vary, so use the thermometer as your real doneness test.
Rest and serve: Let the drumsticks rest for 5 minutes so the juices settle, then serve.
Notes
Pat the drumsticks very dry and use baking powder (not baking soda) in the rub for the crispiest skin. Preheat the basket air fryer, cook in a single layer, and flip halfway. Safe at 165°F, but pull dark meat closer to 175°F for the best texture; air fryer models vary, so check with a thermometer.