save scene and load using binary file

Hi, my game doesnt have main menu, just simply levels, when players opens the game i want to continue from last session scene(level) . how do i create binary file(or using playerprefs) . could you please help me how to save scene and load here in my game using binary file. here is my game code. please help me i am stuck here for last few days

 public class PlatformBuild : MonoBehaviour
 {
     void Awake()
     {
         LoadLevel();
     }
 public void LoadLevel() 
     {
     
         float spawnPosZ = -42.86f;
 
         for (int i = 0; i < PlatformsSize; i++)
         {
             GameObject platform = Instantiate(RandomPlatform, transform);
             platform.transform.localPosition = new Vector3(0, 0, spawnPosZ);
             platform.transform.localEulerAngles = new Vector3(0, 0, UnityEngine.Random.Range(0, 360));
             spawnedPlatforms.Add(platform);
         }   
         GameObject finalPlatformInstance = Instantiate(finalPlatform, transform);
         finalPlatformInstance.transform.localPosition = new Vector3(0, 0, spawnPosZ);
     }
 }

this is my gameManger script,

 public class GameManager : MonoBehaviour
 {
        
  public void NextLevel()
     {        
         LevelCompletedMenu.SetActive(false);            StartCoroutine(LoadFade(SceneManager.GetActiveScene().buildIndex + 1));
 
     }
 
     public void RestartLevel()
     {
         score = 0;
         StartCoroutine(LoadReStart());
         GameOver.SetActive(false);
         StartCoroutine(LoadFade(SceneManager.GetActiveScene().buildIndex));
 
     }

}