Drupal 8 get paragraph parent

$variables['elements']['field_ra']['#object']->get('parent_field_name')->getString();

You can then use it as in a theme suggestion. This will allow you to override paragraphs located in other paragraphs (or other fields)

paragraph–ra–field-r.html

function xxx_theme_suggestions_paragraph_alter(array &$suggestions, array $variables) {
  if(isset($variables['elements']['field_ra'])){
    $suggestions[] = 'paragraph__ra__' . $variables['elements']['field_ra']['#object']->get('parent_field_name')->getString();
  }
}