Preheat the oven to 350°F (175°C).
Wash and dry the produce. Cut the red onion into 8 wedges, seed and chunk the red bell pepper, leave grape tomatoes whole, cut one orange into chunks, and halve the other orange and one lemon for zest and juice.
In a mixing bowl, zest and juice the reserved orange and lemon, then add the olive oil, honey, onion powder, garlic powder, minced garlic, and a pinch of salt; whisk until combined.
Lightly oil a 17x12-inch sheet pan or line it and set aside.
Rinse the chicken if desired, then pat each thigh very dry with paper towels. Season both sides with salt and pepper.
Dip each chicken thigh into the honey-citrus sauce so it is well coated, shake off excess, and arrange the thighs on the prepared sheet pan.
Arrange the onion wedges, red bell pepper chunks, whole grape tomatoes, orange chunks, halved lemon, kalamata olives, and capers around and between the chicken pieces on the pan.
Spoon any remaining honey-citrus sauce over the chicken and vegetables, then tuck fresh rosemary sprigs over the chicken.
Cover the pan tightly with foil and bake for 20 minutes.
Remove the foil and return the pan to the oven; continue roasting for about 30 minutes more, rotating the pan once halfway through, until the chicken is golden and cooked through (internal temperature 165°F/74°C).
Remove from the oven, discard the large rosemary sprigs, and drain off about half of the pan juices if desired.
Garnish with additional green and red olives and fresh rosemary sticks before serving.
