Project_WL/Assets/Script/Ingame/GlobalVolumeMgr.cs

using System.Collections;
using UnityEngine;
using UnityEngine.Rendering;

public class GlobalVolumeMgr : MonoBehaviourSingletonTemplate<GlobalVolumeMgr>
{
    public Volume m_Volume;

    public void Set(int index, float lifetime = 0f)
    {
        if (lifetime > 0f)
            StartCoroutine(Co_Off(lifetime));
    }

    IEnumerator Co_Off(float lifetime)
    {
        m_Volume.enabled = true;
        yield return new WaitForSeconds(lifetime);
        m_Volume.enabled = false;
        Set(0);
    }
}