Preheat the grill to a medium-high temperature of 200°C (400°F).

Pat the chicken legs dry thoroughly to remove excess moisture.

In a mixing bowl, combine olive oil, garlic powder, onion powder, paprika, cayenne pepper, kosher salt, and black pepper. Stir until well blended.

Rub the spice mixture all over each chicken leg, resting it at room temperature for a few minutes.

Clean the grill grates and oil them with a paper towel dipped in vegetable oil.

Place the chicken legs on the hot grill and cook for approximately 25-30 minutes, flipping every 5-10 minutes.

Check for doneness using a meat thermometer; it should read 85°C (185°F).

Let the chicken rest uncovered for about 5 minutes before serving.