Start by using a paper towel, and dry the chicken.
Add the smoked paprika, onion powder, garlic powder, salt, and pepper in a shallow bowl.
Add the hot sauce and buttermilk to a large bowl, and mix well until combined. Add in half of the seasonings.
Pour your buttermilk mixture into a large resealable plastic bag, then place the chicken in the bag. Let soak for about 1-2 hours or even overnight.
Add the cornstarch, baking powder, and the rest of the seasoning mix in a large bowl, and mix well. Remove the piece of chicken from the brine, drain, add your chicken legs, and coat the chicken. Finish breading the chicken, and set them on a wire rack or baking sheet.
Then recoat the chicken with the brine and then dredge the chicken again in the flour mixture.
Preheat the Ninja Foodi to 360 degrees F, place the chicken onto the trivet or the bottom of the air fryer, and then add the lid to the Ninja Foodi; set the cooking time for 20 minutes, flipping halfway during the cooking process. For the best results, brush the chicken's coating with olive oil, or spray it with cooking spray.
Remove when the chicken's internal temperature reaches 165 degrees F, using a meat thermometer.
Serve with a dipping sauce or with additional seasonings