The 'Social Icons' element can be selected below the tab 'Content elements' when creating a new element. (1.12.1)
In the 'General' tab you can see that the content element type 'Social Icons' is selected (1).
The element uses the regular header field (2), that is not visible in frontend.
In 'Additional settings' you can add links to different social networks by adding link address (3). (1.12.2)
As a result you'll see this: