composer require drupal/toolbar_menu
1) create new menu: /admin/structure/menu/add
2) add some menu items
3) add toolbar menu element (menu) /admin/config/user-interface/toolbar_menu/elements
4) add permission for the role (View menu element in the toolbar)
Source:
https://www.webwash.net/how-to-add-menus-using-toolbar-menu-in-drupal-8/