gimm-platformer-project/Assets/Scripts/Goal.cs

using System;
using UnityEngine;
using UnityEngine.SceneManagement;

public class Goal : MonoBehaviour
{
    private Scene currentScene;
    private void Start()
    {
        currentScene = SceneManager.GetActiveScene();
    }

    private void OnCollisionEnter2D(Collision2D other)
    {
        if (other.collider.CompareTag("Player"))
        {
            GetComponent<AudioSource>().Play();
            nextLevel();
        }
    }

    private void nextLevel()
    {
        switch (currentScene.name)
        {
            case "level1":
                SceneManager.LoadScene("level2");
                break;
            case "level2":
                SceneManager.LoadScene("level3");
                break;
            case "level3":
                SceneManager.LoadScene("winScreen");
                break;
        }
    }
}