Check out example codes for "load scene async unity". It will help you in understanding the concepts better.

Code Example 1


Code Example 2

using UnityEngine.SceneManagement;

int buildIndex = 0;
//Load the scene with a build index

Code Example 3

using System.Collections;
using UnityEngine;
using UnityEngine.SceneManagement;public class Example : MonoBehaviour
    void Update()
        // Press the space key to start coroutine
        if (Input.GetKeyDown(KeyCode.Space))
            // Use a coroutine to load the Scene in the background
    }    IEnumerator LoadYourAsyncScene()
        // The Application loads the Scene in the background as the current Scene runs.
        // This is particularly good for creating loading screens.
        // You could also load the Scene by using sceneBuildIndex. In this case Scene2 has
        // a sceneBuildIndex of 1 as shown in Build Settings.        AsyncOperation asyncLoad = SceneManager.LoadSceneAsync("Scene2");        // Wait until the asynchronous scene fully loads
        while (!asyncLoad.isDone)
            yield return null;

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