UnityEngine.SceneManagement.SceneManager.UnloadSceneAsync C# (CSharp) Method

        public static AsyncOperation UnloadSceneAsync(Scene scene)
        {
            bool flag;
            return UnloadSceneNameIndexInternal("", scene.buildIndex, false, out flag);
        }

    IEnumerator LoadSceneGame(int weight)
    {
        Scene scene = SceneManager.GetSceneByName("Game");

        if (scene.isLoaded)
        {
            _asyncOperation = SceneManager.UnloadSceneAsync(scene);
            while (!_asyncOperation.isDone)
            {
                yield return(0);
            }
        }

        _asyncOperation = SceneManager.LoadSceneAsync("Game", LoadSceneMode.Additive);
        _asyncOperation.allowSceneActivation = false;
        yield return(0);

        float progress = 0;

        while (!_asyncOperation.isDone)
        {
            progress = _asyncOperation.progress < 0.9f ? _asyncOperation.progress : 1;

            yield return(progress * weight);

            if (progress >= 0.9f)
            {
                _asyncOperation.allowSceneActivation = true;
            }
        }
    }