get taxonomy term aliased path when its a referenced field in a $node entity
Sure enough I could use the tid or target_id in entity reference lingo and use it to find the URL fromRoute using as route_name entity.taxonomy_term.canonical 

    $tid = $node-&gt;field_category[0]-&gt;target_id;
    $categoryurl = \Drupal\Core\Url::fromRoute('entity.taxonomy_term.canonical', ['taxonomy_term' =&gt; $tid], $options);


find other taxonomy route_names 

might also need to see the Url::fromRoute definition