if a string contains any string (Unity)

I want to do if first child's string contains any child's string, then enable colliders of these same strings. For example: zero element's string and (what if) fourth element's string are same. then these string's collider will enable. How can i do it?

if (letterPanel.childCount > 0)
     {
         string letter = letterPanel.GetChild(0).GetComponent<TextMeshPro>().text;
         letterPanel.GetChild(0).GetComponent<CircleCollider2D>().enabled = true;
         for (int i = 0; i < letterPanel.childCount; i++)
         {
             if (letter.Contains(letterPanel.GetChild(i).GetComponent<TextMeshPro>().text))
             {
                 //enable colliders that same strings
             }
             else
             {
                 //stay as disable except zero element's collider
             }
         }
     }