Check a boolean function without using Update()

I want to check if a bool function is true or false, but I wanna avoid the Update function. I've looked into properties but I could only find stuff for bool variables not bool functions. There becomes the problem of assigning Win() = value; in the property that doesn't work since it's a method, maybe there is a trick to it, any help is appreciated.

 bool Win()
     {
         foreach (GameObject letter in wordUI.playerLetters)
         {
             if (!letter.GetComponentInChildren<TextMeshProUGUI>().enabled) return false;
         }
         return true;
     }

Currently checking constantly in the Update function works but I know it's a terrible idea.

 void Update()
     {
         if (Win()) currentState = State.WIN;
     }