To add a new tab “Manuals” next to description tab. That can be downloadable for that specific item.

The requirement can be achieved by customizing. 

•  We will be creating an item field for providing the PDF link in item record. 
•  The manuals will be stored in file-cabinet in PDF format. 
•  By creating an extension, we will customize the way of tab looking and display the “Manuals” tab in the PDP. 

In Template file:

SASS file:

In .js file:

So, screenshots added below for reference on how it will be displayed on the website. 

If the item doesn’t have any “Manuals” then a message will be displayed.