Display only taxonomy parents from an entity reference field
Create a custom view mode for taxonomy terms and display the taxonomy term as "rendered entity", using your customized view mode.

Then create a Twig template for that special view mode: Assuming your newly created view mode is onlyparents, create a template taxonomy-term--onlyparents.html.twig

There is no field like "parents", so there also is no pre-built field formatter for this. To get the parents, you will need to do some manual preprocessing like

function mymodule_preprocess_taxonomy_term(&amp;$variables) {
  $term = $variables['elements'];
  $parents = \Drupal::entityTypeManager()
    -&gt;getStorage('taxonomy_term')
    -&gt;loadAllParents($term-&gt;id());
  $variables['parents'] = $parents;
}


In Twig you can do something like

{% for parent in parents %}
  {{ parent.label }}
{% endfor %}