Reality Composerで編集

下図のようにビヘイビアを設定
Xcodeで編集

import UIKit
import RealityKit

class ViewController: UIViewController {
    
    @IBOutlet var arView: ARView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // Load the "Box" scene from the "Experience" Reality File
        let boxAnchor = try! Experience.loadBox()

        //追記「tapped」は上記図の赤枠で設定
        boxAnchor.actions.tapped.onAction = handleTapOnEntity(_:)
        
        // Add the box anchor to the scene
        arView.scene.anchors.append(boxAnchor)
    }
    
    //関数を追記
    func handleTapOnEntity(_ entity: Entity?) {
          guard let entity = entity else { return }
          // Do something with entity...
        print(entity) //Do something
      }
}