Yes, the Magento 2 Mega Menu Extension supports multi-level submenus. You can easily create nested submenu structures with multiple levels to organize your menu items in a hierarchical manner.

Read this guide on How to Create Mega Menu in Magento 2 Website to create multi-level submenus using this extension.

Here are the few more resource to help you get most out of this Magento 2 Mega Menu Extension.

• What is a Mega Menu & How to Install Magento 2 Mega Menu Extension
• Best Practices to Simplify your Magento 2 Store Navigation
• Guide to Create Elegant Mega Menu to your Magento 2 Store
• 7 Advantages of Using Mega Menu for eCommerce Business