Example.cs

using System.Collections;
using UnityEngine;

public class Example : MonoBehaviour
{
    private IEnumerator Start()
    {
        Screen.SetResolution( 640, 480, true );

        yield return null;

        Debug.Log( $"変更前：{Display.main.systemWidth} x {Display.main.systemHeight}" );
        Debug.Log( $"変更後：{Display.main.renderingWidth} x {Display.main.renderingHeight}" );
    }
}