Mobile nav submenu

Thanks for reaching out to us with your question.

Unfortunately, Elementor’s Nav Menu widget doesn’t currently allow building a mega menu.

As a workaround, try using one of the available 3rd party mega menu add-ons.
Check out Elementor’s addon list here: https://elementor.com/addons/

Check out one recommendation for such an option from our blog:
https://elementor.com/blog/wordpress-mega-menu/

Let me know if you need further assistance.

Best Regards,