Pat the chicken thighs completely dry with paper towel on both sides. Season with the kosher salt and black pepper. Dry chicken browns; wet chicken steams.
Preheat the air fryer to 380°F for 3 minutes.
Place the thighs in the basket in a single layer, not touching. Cook boneless skinless for 14–16 minutes, flipping at 8. Cook bone-in skin-on for 22–25 minutes, starting skin-side down and flipping at 12. Cook to an internal temperature of 175°F — thighs are dark meat and are more tender at 175–185°F than at the 165°F minimum.
While the chicken cooks, whisk the soy sauce, ketchup, honey, minced garlic, and basil together in a small saucepan.
Simmer over medium-low for 5–6 minutes, stirring, until the sauce thickens enough to coat the back of a spoon. Reserve 2 tablespoons for serving.
Brush the reduced glaze over the cooked thighs and return to the air fryer for 2–3 minutes, until it sets and caramelizes at the edges. Do not glaze earlier — honey scorches well below air fryer temperature.
Rest 3 minutes, then drizzle with the reserved glaze and serve.