Greetings, In Blender's export window for USDZ where you name the file, on the right hand side there are some options. Depending upon what I am doing I put check marks in Export Materials and Bake Textures. I usually end up with something close to what I want. Sometimes the textures just don't look properly in Reality Composer.

I have found out that .rotation is not working for me and I can use .orientation for setting the model in 3D space. I added the toy_biplane.usdz file downloaded from Apple into the Project Navigator. Then I started messing with the code. And reading more and messing more. This is where I am for now. I commented out things as I went along, just in case... 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()         let planeAnchor = AnchorEntity(plane: .horizontal)         // Add the box anchor to the scene         arView.scene.anchors.append(planeAnchor)          //        if let box = boxAnchor.findEntity(named: "lid") { //            let radians = -45.0 * Float.pi / 180.0 //            box.transform.rotation += simd_quatf(angle: radians * 0, axis: SIMD3<Float>(1,0,0)) //        }         let biplane = try? Entity.load(named: "toy_biplane.usdz")         planeAnchor.addChild(biplane!)         // var flyingBiplane = biplane?.transform         let radians = 90.0 * Float.pi / 180.0         biplane?.transform.translation += SIMD3<Float>(0.0, 1.0, 0.0)  // This is Meters!!!  not CM. //        biplane?.transform.rotation += simd_quatf(angle: radians, axis: SIMD3<Float>(0,1,0))         biplane?.orientation = simd_quatf(angle: radians, axis: SIMD3(x: 0, y: 1, z: 0))         biplane?.transform.scale *= 0.5     } } I am starting to get the result I am looking for.