Adding Custom Link
When creating a menu with WordPress, you can decide that a menu item links to an external page by adding a Custom Link.
Open Link in New Tab
You can change the target of this link, so that it opens in a new browser tab. For that you need to check an option located below the Navigation label field of the menu item and named “Open link in a new tab“, as illustrated in the following screenshot.
Show Open Link in new tab Option
If this option is not visible, it means that it’s not enabled in the menu screen option. Simply follow those steps to activate the option :
1. Click on the Screen Options link in the top right corner of the menu admin screen.
2. Check the “Link Target” option : this will reveal the “Open link in a new tab” option.