Open a link in a new tab in the menu
In my case I utilized hook_link_alter() to accomplish this.
Situation: in my menu links, I only need Contact Us to open in a new tab.

&lt;?php
function MYMODULE_link_alter(&amp;$variables) {
  if (!$variables['url']-&gt;isRouted()) {
    $uri = $variables['url']-&gt;getUri();
    // Only want the Contact Us to open in new tab.
    if ($uri == 'base:contact-us') {
      $variables['options']['attributes'] = ['target' =&gt; '_blank'];
    }
  }
}