Mega menu

Shopify allows you to nest menus and menu items in the Online Store Navigation Editor. You can build dropdown menus by creating or moving menu items so that they are “Nested” below a top-level item. Follow these steps to add Navigation:

From your Shopify admin, go to Online Store > Navigation.
Click the name of your main menu.
Choose one of the menu items to be the header for your dropdown menu, or add a new menu item to be the header. If you don't want the header to link to anything, then you can enter '#' in the Link field when you add the menu item.
Add menu items to include in the new dropdown menu. Click Add menu item enter the name of the menu item, and enter or select a destination for the link.
Click and drag the menu items to nest below the header item.
Click the Save menu.

There are multiple types of Mega menus you can add to your store

Select the Header from the theme editor.
Click on "Add block.", user can create three types of blocks: Mega menu product, Mega menu submenu/gallery, Mega menu blog

Click on "Add block" and add the Mega menu product block.

Mega menu with the product allows you to add products with a submenu. Please follow the screenshot.

Typing the same menu name in the Menu label will connect this menu to the Mega menu that is built through the theme editor. Check the below screenshot.

Click on "Add block" and add the Mega menu submenu/gallery block.

This Mega menu allows you to add submenus and a gallery. Please follow the below screenshot.

To a add submenu, go to Online Store > Navigation.
Click the name of your Main menu.
Add menu items to include in the new dropdown menu. Click Add menu item enter the name of the menu item, and enter or select a destination for the link.
Click and drag the menu items to nest below the header item.
Click the Save menu.