using UnityEngine;
private float ratio = 1f;
private float panelW;
private float panelH;

UIRoot root = GameObject.FindObjectOfType<UIRoot>();
if (root != null) {
    // 實際尺寸和設計尺寸比例
    ratio = (float)root.activeHeight / Screen.height;            
}

// 設計尺寸
panelW = transform.GetComponent<UIPanel>().width;
panelH 
 
= transform.GetComponent<UIPanel>().height;

// 實際尺寸
width = panelW * ratio;
height = panelH * ratio;

Unity獲取實際尺寸和設計尺寸