You need to use add_menu_page and add_submenu_page to display menu and sub menu.
For more, refeir https://developer.wordpress.org/reference/functions/add_menu_page/
https://developer.wordpress.org/reference/functions/add_submenu_page/
You need to use add_menu_page and add_submenu_page to display menu and sub menu.
For more, refeir https://developer.wordpress.org/reference/functions/add_menu_page/
https://developer.wordpress.org/reference/functions/add_submenu_page/