I want to have a clean animation coded per a script and therrfor i create two ui images, and alll works fine besides the images are displayed in bottom left corner. I tried to move it with the help of all Functions Unity gives us for (expect Move Towards because i dont want a animation inside of it). What am I doing wrong?

using System.Collections;
using UnityEditor;
using UnityEngine;
using UnityEngine.Rendering;
using UnityEngine.SceneManagement;
using UnityEngine.UI;

public class SceneController : MonoBehaviour
{
    public SceneAsset scene;

    public Sprite maskSprite;
    public Material maskMaterial;
    public Material backgroundMaterial;

    private float time;

    private void Start()
    {
        StartCoroutine("AnimationController");
    }

    private Image createMesch(string name, Material material) {
        
        GameObject child = new GameObject(name);
        child.transform.SetParent(gameObject.transform);
        Image childMaterial = child.AddComponent<Image>();
        childMaterial.material = material;

        // Copied from the internet. Should Center the Pivot and anchor
        childMaterial.rectTransform.anchorMin = new Vector2(0.5f, 0.5f);
        childMaterial.rectTransform.anchorMax = new Vector2(0.5f, 0.5f);
        childMaterial.rectTransform.pivot = new Vector2(0.5f, 0.5f);

        return childMaterial;

    }

    private IEnumerator AnimationController() {
        Image mask = createMesch("Transition_Mask", backgroundMaterial);
        mask.sprite = maskSprite;
        Image background = createMesch("Transition_Background", maskMaterial);

        //Doesnt work
        background.rectTransform.position = Vector3.zero;

        Vector2 screenSize = new Vector2(Screen.width, Screen.height);
        print(background.rectTransform.position);
        background.rectTransform.sizeDelta = screenSize;
        background.color = Color.black;

        float maskSize = Mathf.Sqrt(Mathf.Pow(Screen.width, 2) + Mathf.Pow(Screen.height, 2));
        Vector2 targetSize = new Vector2(maskSize, maskSize);



        // yield return new WaitForSeconds(5);


        while (time < 1)
        {
   
            mask.rectTransform.sizeDelta = Vector2.Lerp(targetSize, Vector3.zero, time);
            yield return null;
            time += Time.deltaTime / 0.8f;
        }

  
        yield return new WaitForSeconds(2);
        time = 0;
  
        while (time < 1)
        {
   
            mask.rectTransform.sizeDelta = Vector2.Lerp(Vector2.zero, targetSize, time);
            yield return null;
            time += Time.deltaTime / 0.8f;
        }

    }

    private void OnTriggerEnter(Collider other)
    {
        SceneManager.LoadScene(scene.name);
    }

}