Preheat the air fryer to 360°F (180°C) so it is ready when you place the frozen thighs inside.
Arrange the 3 frozen chicken thighs in a single layer in the air fryer basket skin side up, avoiding overlap.
Lightly coat the skin of each thigh with olive oil spray, then season the top with freshly ground black pepper and 1 tablespoon herb blend or all-purpose seasoning.
Flip each thigh using tongs, spray the other side with oil, and season that side with pepper and the herb blend as well.
Cook at 360°F for 25 minutes, flipping the thighs halfway through cooking; spray with more oil if the skin looks dry.
After 25 minutes check the internal temperature in the thickest part; it should read 165°F (74°C). If not, continue cooking for an additional 5–10 minutes and recheck.
For extra-crispy skin, increase the air fryer temperature to 380°F and cook 3–5 more minutes, then remove and serve hot.