Yes, Magento 2 Mega Menu Extension is compatible with Magento 2.3.

Read this How to Create Mega Menu in Magento 2 Website to setup 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