Preheat the air fryer to 375°F (190°C) for 3 minutes.Peel the onions and slice them into ½-inch-thick rings. Separate the rings.Prepare three bowls: one with flour, one with beaten eggs and milk, and one with panko breadcrumbs, Parmesan, garlic powder, onion powder, smoked paprika, salt, and pepper.Coat each onion ring in flour, dip it into the egg mixture, then press it firmly into the breadcrumb mixture until evenly coated.Arrange the coated onion rings in a single layer in the air fryer basket. Lightly spray both sides with cooking oil.Air fry for 10–12 minutes, flipping halfway through, until golden brown and crispy.Let the onion rings rest for 2 minutes before serving with your favorite dipping sauce.