Get paragraph type of child field item

get_paragraph_type_from_field.php

<?php

/**
 * Implements hook_preprocess_HOOK for field--field-structured-content-section.html.twig
 */
function TEMPLATE_preprocess_field__field_structured_content_section(&$variables) {
  $items = $variables['items'];
  foreach ($items as &$item) {
    $paragraph = $item['content']['#paragraph'];
    $para_type = $paragraph->getType();
  }
}