Scene Loader in Unity

For loading scenes:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.SceneManagement;

public class SceneLoader : MonoBehaviour
{
    [SerializeField] int startScene = 0;

    public void LoadNextScene()
    {
        int currentSceneIndex = SceneManager.GetActiveScene().buildIndex;
        SceneManager.LoadScene(currentSceneIndex + 1);
    }

    public void ReturnStartScene()
    {
        SceneManager.LoadScene(startScene);
    }

    public void QuitGame()
    {
        Application.Quit();
    }

    public void LoadGameOver()
    {
        SceneManager.LoadScene(2);
    }
}