Online Store 2.0-compatible themes can divide the product description to display a portion below the product media gallery and span the full width of the product page.
Add the split code to product description HTML, then reposition the split with the product page template's sections.
Add split code to the product description HTML
Go to Products to edit your product Description. Click Show HTML to open the HTML view.
Place this tag in your product description at the point where you'd like the description to 'split' into the two components:
<!-- split -->
The split tag is only compatible with the Default product page template
Reposition the split with product page section
Consider adding a Custom liquid section to control the split's position on the product page template.
Add a custom liquid section to the template
In the theme editor (Customize), open Products, then Default product with the page selector.
Select (+) Add section, the select Custom liquid.
Paste the code
Click to open the section's settings, then add the following code to the Custom liquid field:
{{ product.description | split: '<!-- split -->' | last }}
Reposition the custom liquid section
Click, hold, then drag the section with your cursor to reposition it on the product page template.