/**
 * Include a ClassicPress page on order received page
 */

add_action('woocommerce_thankyou', 'cc_custom_order_received_page', 5);

function cc_custom_order_received_page() {

  $page_id = 1643; 
  $page_object = get_post($page_id);
  echo $page_object->post_content;

}