How to get child products from Layer Class Magento 2

14219 is the ID of the parent product. 14217, 14218 are the child product ids but the collection only returns the parent product,I need to get from the Layer which products visibility is VISIBILITY_NOT_VISIBLE , can anyone help?
Thanks

class Layer extends MagentoCatalogModelLayer {

public function getProductCollection()
{
    $collection = parent::getProductCollection();
    $collection->addAttributeToSelect('*');
    $collection->addAttributeToFilter('visibility', MagentoCatalogModelProductVisibility::VISIBILITY_NOT_VISIBLE);
    $idArray = [14219,14217, 14218];
    if (!empty($idArray)) {
        $collection->addAttributeToFilter('entity_id', ["in"=>$idArray]);
    }
    return $collection;
}

}