You can make your Mega Menu responsive by using a Magento 2 Mega Menu Extension. Such extensions adapt the menu layout for different screen sizes, providing an optimal viewing and navigation experience on various devices.

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