Handling multiple tags

My idea is to add multiple gameobjects with different tags and I would like to use List for it, more like using a List as a method. This is what I've had so far.

 public void FindObjectsWithTags<GameObject>(string[] tags)
     {
         var compList = new List<GameObject>();
         for (int i = 0; i < tags.Length; i++)
         {
             var taggedObjects = GameObject.FindGameObjectsWithTag(tags[i]);
             compList.AddRange(taggedObjects);
         }
     }

I've used List many times, but I haven't do List as a method before, plus there's an error on on "var taggedObject = ...." lines, so I'm kinda lost right now. Could someone point me to the right direction? I really want to use this List method because it's the most efficient way to handle multiple tags. Sorry for this idk, lame question maybe? Thanks.