https://elizabethfreemanweb.com/how-to-add-google-structured-data-to-wordpress-menus/ Wanted result in HTML <span itemscope="itemscope" itemtype="http://schema.org/SiteNavigationElement"> <ul id="menu-main" class="nav"> <li class="menu-main"

functions.php

<?php
/* Add the following to the Theme header.php (typically) */
 <nav itemscope="itemscope" itemtype="http://schema.org/SiteNavigationElement" role="navigation">
  wp_nav_menu(['theme_location' => 'primary_navigation', 'walker' => MyNavWalker(), 'menu_class' => 'nav']);
</nav

/* Add this to the functions.php . This adds the 'url' attribute to every <a> link in the menu */

function add_menu_attributes( $atts, $item, $args ) {
  $atts['itemprop'] = 'url';
  return $atts;
}
add_filter( 'nav_menu_link_attributes', 'add_menu_attributes', 10, 3 );