DontDestrouOnLoad

using UnityEngine;
 
public class DontDestroyOnLoad : MonoBehaviour {
 
void Start() {
DontDestroyOnLoad(this);
}
}

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class SoundPlayer : MonoBehaviour
{
    private static SoundPlayer _instance;
    private AudioSource _audioSource;
 
    void Awake()
    {
        _instance = this;
    }
 
    void Start()
    {
        _audioSource = GetComponent<AudioSource>();
        _audioSource.Play();
        _audioSource.loop = true;
        DontDestroyOnLoad(this);
    }
 
 
    public static SoundPlayer CreateSoundPlayer()
    {
        if (_instance == null) {
            var player = GameObject.Instantiate(Resources.Load<GameObject>("SoundPlayer"));
            _instance = player.GetComponent<SoundPlayer>();
        }
        return _instance;
    }
    
}

if (_instance != null) Destroy(this);

    private static SoundPlayer _instance;
 
    public static SoundPlayer Instance
    {
        get
        {
            return _instance;
        }
    }
 
 
    private void Awake()
    {
        if (_instance == null)
            _instance = this;
        else
        {
            DestroyImmediate(this);
        }
    }