Preheat oven to 425°F. Line a large rimmed sheet pan with parchment.
Dry the chicken well. Toss with 1 tbsp oil, half the salt, half the pepper, half the Italian seasoning, and the paprika. Arrange skin-side up on the pan.
Combine potatoes, carrots, broccoli, onion, and bell pepper in a bowl. Add remaining oil, garlic, lemon juice, remaining seasonings, and red pepper flakes. Toss to coat.
Spread the vegetables around the chicken in a single layer.
Roast 20 minutes.
Stir the vegetables and spoon pan juices over the chicken. Roast 15–20 minutes more, until chicken reaches 165°F and potatoes are tender.
Broil 2–3 minutes for extra-crisp skin, if desired. Rest 5 minutes, then sprinkle with parsley and serve.