class BaseUIController : MonoBehaviour {
    
    public void DrawUI() {
        // Draw common hud
    }

}

...

class MenuUIController : BaseUIController {
  
  public GameObject UIMenuPane;
  public GameObject UIMenuStart;

  public override void DrawUI() {
    base.DrawUI();
    if(something)
        UIMenuPane.GetComponent<Button>().active = true;
    
  }

}

if(GUI.Button(new Rect(0, 0, 100, 30), "Button") && buttonActive) {
// Do something
}