Any flaky white fish, like hake or cod, can be substituted for sea bass.
Preheat oven to 450 degrees. On a rimmed baking sheet, toss kale with 2 tablespoons oil; season with salt and pepper. Roast, tossing once, until beginning to crisp, 6 to 8 minutes. Remove from oven; add beans and 1 tablespoon oil to sheet and toss to coat. Season fish on both sides with salt and pepper; place on top of kale mixture and drizzle with oil. Roast until fish is opaque and flaky, 10 to 12 minutes.
Meanwhile, stir together orange juice, vinegar, onion, and olives. Stir in remaining 5 tablespoons oil; season with salt and pepper. Transfer fish to a plate; drizzle half of vinaigrette over kale and beans. Divide evenly among plates, top each with fish, and serve, with remaining vinaigrette spooned over top.