How can I take a collision from a layermask to change a game object?,How can I make a Collision with a layermask?

Hi, So I am making a tag game with FPS style of Movement. My problem is that I want to have the tagger collide with the non-tagged player and turn that player into a tagged (infection). I am pretty new to Unity and coding itself and I am using a LayerMask to decide if the player is tagged or not. I also want the colors to change depending on if the player is tagged or not. and I have a "Looks like it would work" script by taking the information that the collision the provides to decide color. If what I am doing is totally wrong or inefficient please let me know. Thanks so much.

Here is my script.

 public Material tagged;
 public Material notTagged;

 bool isTagged;
 public LayerMask Tag;

 Rigidbody rb;


 // Start is called before the first frame update
 void Start()
 {
     rb.GetComponent<Rigidbody>();
 }

 // Update is called once per frame
 void Update()
 {

     //Decides the color of tagged or non-tagged 
     if (isTagged)
     {
         transform.GetComponent<Renderer>().material = tagged;
     }
     else if (!isTagged)
     {
         transform.GetComponent<Renderer>().material = notTagged;
     }
 }

 private void OnTriggerEnter(Collider col)
 {
     //Decides if isTagged is true or false
 }