How to add delay before loading the next level?

Unity Engine
1

So I am quite new to Unity (working on first project), and I was following along with a Jason Weimann tutorial, eventually I finished and now have 3 levels. It works as a mimic of angry birds, and it is coded so that as soon as all the monsters are destroyed, the next level is loaded. However, I wanted to adjust it so that there was a small delay, for the satisfaction of completing the level, etc., but I could not figure out how to do this. I was researching and found something about coroutines, but I’m not exactly sure how they work, I am using visual studio, and sorry in advance for the messy coding and formatting haha

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

public class LevelController : MonoBehaviour
{
    private bool _birdLaunched;
    private float _timeSittingAround;
    private bool _birdTooLong;

    private static int _nextLevelIndex = 1;
    private monster[] _enemies;

    private void OnEnable()
    {
        _enemies = FindObjectsOfType<monster>();
    }

    // Update is called once per frame
    void Update()
    {

        foreach (monster monster in _enemies)
        {
            if (monster != null)
                return;

        }


        Debug.Log("You killed all enemies");



        int v = _nextLevelIndex++;
        string nextLevelName = "Level" + _nextLevelIndex;
        SceneManager.LoadScene(nextLevelName);


    }
}
2

The following code is a very basic solution.
Define a float variable that will count the time since all enemies have been killed (levelLoadUpdate). If all enemies have been killed add Time.deltaTime to it. If the variable is below a threshold return, else load the level.

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.SceneManagement;
public class LevelController : MonoBehaviour
{
    private bool _birdLaunched;
    private float _timeSittingAround;
    private bool _birdTooLong;
    private static int _nextLevelIndex = 1;
    private monster[] _enemies;
    private void OnEnable()
    {
        _enemies = FindObjectsOfType<monster>();
    }

    float levelLoadUpdate;
    // Update is called once per frame
    void Update()
    {
        foreach (monster monster in _enemies)
        {
            if (monster != null)
                return;
        }
       levelLoadUpdate += Time.deltaTime;
       if(levelLoadUpdate < 2f)
            return;
        Debug.Log("You killed all enemies");
        int v = _nextLevelIndex++;
        string nextLevelName = "Level" + _nextLevelIndex;
        SceneManager.LoadScene(nextLevelName);
    }
}
3

For brackeys, what he did was create a function with SceneManager.LoadScene(“nextLevelName”, or SceneManager.GetActiveScene().buildIndex +1 or something)

public void NextLevel()
{
SceneManager.LoadScene("nextLevelName")
}

Basically take that method, stuff it into a function. Then, whenever you want to go to the next scene, use Invoke("NextLevel", 5f); unity will wait 5 seconds before calling NextLevel(), which gives 5 seconds time for the player before the next scene.

tldr use a function to call the next scene, use Invoke(“Functionname”, delayinfloat); to create a delay.