How do I change the node view mode before rendering?
If you want to make sure that a content type is always rendered with a custom view mode, use the following hook in a module. (I assume the module machine name is mymodule.)

mymodule.module

/**
 * Implements hook_entity_view_mode_alter().
 */
function mymodule_entity_view_mode_alter(&amp;$view_mode, $entity, $context) {
  if ($entity-&gt;getEntityTypeId() == 'node' &amp;&amp; $entity-&gt;bundle() == 'my_content_type') {
    $view_mode = 'my_custom_view_mode';
  }
}