(Drupal 8.x) Programmatically load entities by type and build an HTML string consisting of teaser views.

drupal_entities_to_html.php

<?php

// Note that I'm building an HTML string for illustrative purposes only since 
// best practice is to allow the twig templates to build HTML from the 
// structured render arrays.

$html = '';

$storage = \Drupal::entityManager()->getStorage('notice');
$result = \Drupal::entityQuery('notice')
  ->execute();

$notices = $storage->loadMultiple($result);

if (!empty($results)) {
  $view_builder = \Drupal::entityManager()->getViewBuilder('notice');
  foreach ($notices as $entity) {
    $render_array = $view_builder->view($entity, 'teaser');
    $html .= \Drupal::service('renderer')->renderPlain($render_array);
  }
}

kint($html);

?>