Preheat the oven to 400°F.
In a 9 × 13-inch baking dish, whisk together the oil, basil, oregano, garlic powder, salt, chili powder, and black pepper.
Pat the salmon dry and place in the baking dish. Swirl the fish to coat with the spiced oil. Transfer to a plate.
Mix the broth and orzo in the dish. Set the feta block in the center of the dish and surround with the cherry tomatoes and olives. Bake until the orzo is al dente and the tomatoes are softened, 23 to 25 minutes.
Stir in the spinach and lemon juice, breaking up the feta and incorporating it into the orzo as you stir. Arrange the fish over the orzo.
Bake until the salmon is opaque and easily flakes with a fork, 9 to 11 minutes.
Divide the orzo among four plates and top each with a piece of salmon.
