This video tutorial will show how to make specific menu open in a new tab in WordPress.
In WordPress admin panel navigate to Appearance -> Menus, open a menu you need:
Click on Screen Options in the top right, select Link target:
Choose specific Menu Items which you want to be opened in a new tab and then press Open link in a new tab, when done press Save menu button:
Go back to your site to test the menu.
Feel free to check the detailed video tutorial below: