使用add_submenu_page 和设置$parent_slug 到null:

add_action(\'admin_menu\', \'wpdocs_register_my_custom_submenu_page\');

function wpdocs_register_my_custom_submenu_page() {
    add_submenu_page( 
        null,
        \'My Custom Submenu Page\',
        \'My Custom Submenu Page\',
        \'manage_options\',
        \'my-custom-submenu-page\',
        \'my_custom_submenu_page_callback\',
    );
}