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

Code Example 1

//for unity c#
using UnityEngine.SceneManagement;
.....
SceneManager.LoadScene(SceneManager.GetActiveScene().buildIndex + 1);

Code Example 2

//For C# in unity
UnityEngine.SceneManagement;
....
SceneManager.LoadScene(SceneManager.GetActiveScene().buildIndex + 1);

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