Snippet to get term by name and vid or create new if it does not exist

This logic could be useful for migration, deploy hooks etc.

 /**
 * Helper function to get/create term by name and vid.
 *
 * @param string $vid
 *   Taxonomy vocabulary machine name.
 * @param string $term_name
 *   Taxonomy term name.
 *
 * @return int
 *   Taxonomy term id.
 */
function _get_term_tid_by_name_and_vid(string $vid, string $term_name) {
  $term_storage = \Drupal::service('entity_type.manager')->getStorage('taxonomy_term');

  // Trying to get existing term id.
  $term_tid = $term_storage->getQuery()
    ->condition('vid', $vid)
    ->condition('name', $term_name)
    ->execute();

  if ($term_tid) {
    return reset($term_tid);
  }
  else {
    // Creating a new term if it doesn't exist.
    $new_term = $term_storage->create([
      'vid' => $vid,
      'name' => $term_name,
      'status' => 1,
      'uid' => 1,
    ]);
    $new_term->save();
    return $new_term->id();
  }
}