Quit App in key Esc(PC) a.k.a Back Button on Android

QuitApp.cs

void Update()
{
    if (Input.GetKeyDown(KeyCode.Escape))
        {
            OnClickBackButtonQuit();
        }
}
    bool isFirstPress = false;
    float timeFirstPress;
    
 void OnClickBackButtonQuit()
    {
        if (!isFirstPress)
        {
            timeFirstPress = Time.realtimeSinceStartup;
            //Do Something
            //OnShowBadInternet("Press Back again to quit Application!", 3);
            isFirstPress = true;
        }
        else
        {
            var timeDoublePress = Time.realtimeSinceStartup - timeFirstPress;
            isFirstPress = false;
            if (timeDoublePress < 3)
            {
                Application.Quit();
                print("Quit");
            }
        }
    }