Step-1: At first, Go to Mega Menu -> Add New. Enter the menu name and choose the template Elementor Canvas. Then click on the publish button.
Step-2: Edit the page with Elementor and update it.
If the Elementor is not enabled in your editor, go to Elementor -> Settings page. Check the Mega Menu option and click on the Save Changes button.
Step-3: When the mega menu page is done, go to the Appearance -> Menus page. From the left sidebar select the mega menu and click on the Add to Menu button.
Drag the menu item under the parent menu item.
Step-4: Then add CSS class mega-menu in the parent menu item.
If the CSS Classes input field doesn’t show, enable the CSS Classes field from the top Screen Options.
Once the CSS class mega-menu is added, click on the Save Menu button. That’s all.