Cria menus padrão com itens (WP)

functions.php

<?php
if ( ! function_exists( 'my_theme_setup' ) ) {
  function my_theme_setup() {
    //Ref. https://developer.wordpress.org/reference/functions/wp_create_nav_menu/
    
    $menu_name   = 'Menu 1';
    $menu_exists = wp_get_nav_menu_object( $menu_name );
    
    if( !$menu_exists ) {
        $menu_id = wp_create_nav_menu($menu_name);
     
        //adiciona alguns itens default, se quiser
        wp_update_nav_menu_item($menu_id, 0, array(
          'menu-item-title'   =>  __( 'Home', 'my-theme' ),
          'menu-item-classes' => 'home',
          'menu-item-url'     => home_url( '/' ), 
          'menu-item-status'  => 'publish'
        ));
        wp_update_nav_menu_item($menu_id, 0, array(
          'menu-item-title'   =>  __( 'Contato', 'my-theme' ),
          'menu-item-classes' => 'contato',
          'menu-item-url'     => home_url( '/contato/' ), 
          'menu-item-status'  => 'publish'
        ));
    }
  }
}
 
add_action( 'after_setup_theme', 'my_theme_setup' );