Preheat your oven to 425°F (220°C) and line a baking sheet with parchment paper or lightly grease it with cooking spray.
In a large bowl, combine the olive oil, garlic powder, onion powder, smoked paprika, dried oregano, salt, black pepper, and red pepper flakes (if using). Mix well to create a marinade.
Add the chicken thighs to the bowl and toss them in the marinade until they are evenly coated. Let them marinate for at least 15 minutes for better flavor.
Arrange the marinated chicken thighs in a single layer on the prepared baking sheet.
Bake in the preheated oven for 25-30 minutes or until the chicken is cooked through and reaches an internal temperature of 165°F (75°C).
Remove from the oven and drizzle with fresh lemon juice. Let the chicken rest for 5 minutes before slicing.
Garnish with chopped fresh parsley before serving.