Playing a button pressed animation on a box

Well, designing the UI for various resolutions is difficult, but once you understand anchoring and the CanvasScaler component, it becomes a lot easier. And with OnGUI() you still have the same problem, but there you have to change code to move the UI, and calculate with resolution and ratios...

Check out this Unity manual about how to design for various resolutions, it is not perfect, but it explains the basics well.

That's actually really easy, just add this script to the UI element you want to move:

 public class AnchorIn3D : $$anonymous$$onoBehaviour {
 
     [SerializeField] private RectTransform ownRectTransform = null;
     [SerializeField] private Transform target = null;
     public void SetTarget (Transform value) { target = value; }
 
     [SerializeField] private Vector3 offset = Vector3.zero;
     public void SetOffset (Vector3 value) { offset = value; }
 
     private void Awake () {
         if (ownRectTransform == null) { ownRectTransform = GetComponent<RectTransform>(); }
     }
 
     private void Update () {
         if (ownRectTransform != null && target != null) {
             ownRectTransform.position = Camera.main.WorldSpaceToScreen(target.position + offset);
         }
     }
 }