Show pages with a specific template when user is logged-in
The most basic way of providing a custom template for a node that meets certain criteria, is using theme hook suggestions.

You can for example add a custom theme suggestion by implementing hook_theme_suggestions_HOOK_alter() in a custom module. There you can check whether your criteria are met and add a custom theme suggestion, if they are:

/**
 * Implements hook_theme_suggestions_HOOK_alter().
 */
function MYMODULE_theme_suggestions_node_alter(array &amp;$suggestions, array $variables) {

  if (
    // Do your checks here, e.g authenticated user?
    \Drupal::currentUser()-&gt;isAuthenticated()
  ) {
    // Add your custom template here. The following
    // example would apply to 'my-node.html.twig'.
    $suggestions[] = 'my_node';
  }

}