Create multilevel submenu in Wordpress

How can I create a SubMenu in a SubMenu already exists? Imean i want to have 3 levels or more in the admin bar menu in Wordpress, is that possible?

`public function admin_menu()
{
    add_menu_page(
        'menu1',
        'menu1',
        'manage_options',
        'manage_menu1',
        array($this, 'func1'),
        'dashicons-welcome-widgets-menus',
        24
    ); add_submenu_page(
        'manage_menu1',
        'sub menu1',
        'sub_menu1',
        'manage_options',
        'manage_menu1',
        array($this, 'func2'),
        'dashicons-testimonial',
        1
    );`