CODE EXAMPLE FOR PHP

Drupal 9 Get taxonomy term objects by vocabulary machine name vid

try {
  $terms = Drupal::entityTypeManager()->getStorage('taxonomy_term')->loadByProperties(['vid' => 'my_vocablary_machine_name']);
} catch (Exception $e) {
  throw new HttpException(400,'Error upon selection of terms/session_tracks. ' . $e->getMessage());
}