Preheat the oven to 425°F (220°C).
In a large bowl, combine the baby potatoes, carrots, red bell pepper, and red onion.
Add 2 tablespoons of olive oil, 1/2 teaspoon salt, 1/4 teaspoon black pepper, 1/2 teaspoon garlic powder, 1/2 teaspoon dried thyme, and 1/2 teaspoon dried oregano to the vegetables. Toss well to coat evenly.
Arrange the seasoned vegetables in a single layer on a large rimmed sheet pan.
Pat the chicken thighs dry with paper towels. In a small bowl, mix the remaining 1 tablespoon olive oil, 1/2 teaspoon salt, 1/4 teaspoon black pepper, 1/2 teaspoon garlic powder, 1 teaspoon smoked paprika, 1/2 teaspoon dried thyme, and 1/2 teaspoon dried oregano.
Rub the spice mixture all over the chicken thighs, making sure to get under the skin where possible.
Place the chicken thighs skin-side up on top of the vegetables on the sheet pan, spacing them evenly.
Roast in the preheated oven for 35 minutes, or until the chicken reaches an internal temperature of 165°F (74°C) and the vegetables are tender and caramelized.
If desired, broil for an additional 2-3 minutes to crisp the chicken skin further, watching carefully to prevent burning.
Remove from the oven and let rest for 5 minutes.
Sprinkle chopped fresh parsley over the chicken and vegetables before serving.