use \Concrete\Core\Entity\Attribute\Value\Value\SelectValueOption;
$tagValues = array();
$importTags = explode(",", $tags);
$ak = CollectionAttributeKey::getByHandle('tags');
 
$orm = \Database::connection()->getEntityManager();
$repository = $orm->getRepository('\Concrete\Core\Entity\Attribute\Value\Value\SelectValueOption');
if ($ak) {
   $existingList = $ak->getAttributeKeySettings()->getOptionList();
}
 
foreach ($importTags as $tag) {
   if (isset($existingList) && is_object($existingList)) {
      $tagValueObject = $repository->findOneBy([
         'list' => $existingList,
         'value' => $tag,
      ]);
   } else {
      $tagValueObject = $repository->findOneByValue($tag);
   }
 
   if (!is_object($tagValueObject)) {
      $displayOrder = 0;
      if ($existingList) {
         $displayOrder = count($existingList->getOptions());
      }
      $tagValueObject = new SelectValueOption();
      $tagValueObject->setOptionList($existingList);
      $tagValueObject->setDisplayOrder($displayOrder);
      $tagValueObject->setSelectAttributeOptionValue(trim($tag));
      $tagValueObject->setIsEndUserAdded(true);
   }
 
   if (is_object($option)) {
      $tagValues[] = $tagValueObject;
   }
}
$newPage->setAttribute('tags', $tagValues);