あらゆる画面に合う UI（ノッチ込み）

using UnityEngine;

[RequireComponent(typeof(RectTransform))]
public class SafeAreaFitter : MonoBehaviour
{
    RectTransform rt;
    Rect last;

    void Awake()
    {
        rt = GetComponent<RectTransform>();
        Apply();
    }

    // The safe area changes when the phone rotates, so do not do this once.
    void Update()
    {
        if (Screen.safeArea != last) Apply();
    }

    void Apply()
    {
        last = Screen.safeArea;

        // Anchors are 0–1 fractions of the screen, so divide by the screen size.
        Vector2 min = last.position;
        Vector2 max = last.position + last.size;
        min.x /= Screen.width;  min.y /= Screen.height;
        max.x /= Screen.width;  max.y /= Screen.height;

        rt.anchorMin = min;
        rt.anchorMax = max;
        rt.offsetMin = rt.offsetMax = Vector2.zero;
    }
}