Function for querying sibling pages that share same parent

sibling-pages-query.php

<?php

function sibling_pages_query() {
	$parentPageObject = get_page_by_title( 'Parent Page' ); // Replace with parent page title
	$output = '';
    
  if ( $parentPageObject ) {
    $subPagesArray = get_pages( 
                        array( 
                            'child_of' => $parentPageObject->ID, 
                            'sort_column' => 'menu_order', 
                            'sort_order' => 'asc' 
                        ) 
                    );

		foreach( $subPagesArray as $subPage ) {
			$output .= '<li><a href="'. get_page_link( $subPage->ID ) .'">'. $subPage->post_title .'</a></li>';
    }
  } else {
      $output .= '<li>Coming Soon</li>';
  }
  
  return '<div class="custom-page-siblings-loop"><ul>'. $output .'</ul></div>';
}	

?>