Activating a prefab in the scene by find it over a tag?

Hello everyone, i want to activating a prefab. To do this i want to use a tag, to find the GameObject and then use SetActive(true) to set set it active. I tried this code but it doesnt work.

     private int ActiveCannon;
     public GameObject Cannon1;
     public GameObject Cannon2;
     public GameObject Cannon3;
     public GameObject Cannon4;
     public GameObject Cannon5;
     public GameObject Cannon6;
     
     void Start () {
     ActiveCannon = PlayerPrefs.GetInt("ActiveCannon");

             if (ActiveCannon == 1)
             {
                 Cannon1 = GameObject.FindWithTag("Cannon1");
                 Cannon1.SetActive(true);
             }
             if (ActiveCannon == 2)
             {
                 Cannon2 = GameObject.FindWithTag("Cannon2");
                 Cannon2.SetActive(true);
             }
             if (ActiveCannon == 3)
             {
                 Cannon3 = GameObject.FindWithTag("Cannon3");
                 Cannon3.SetActive(true);
             }
             if (ActiveCannon == 4)
             {
                 Cannon4 = GameObject.FindWithTag("Cannon4");
                 Cannon4.SetActive(true);
             }
             if (ActiveCannon == 5)
             {
                 Cannon5 = GameObject.FindWithTag("Cannon5");
                 Cannon5.SetActive(true);
             }
             if (ActiveCannon == 6)
             {
                 Cannon6 = GameObject.FindWithTag("Cannon6");
                 Cannon6.SetActive(true);
             }   }

Sorry for my bad english.