They're just normal links made with HTML but also with a bold tag.
The code goes something like this (( replace [ for < and ] for > ))

[center]

[b][a href="https://www.instagram.com/digitalrowye/"]Instagram[/a]
[a href="https://www.youtube.com/channel/UCiOVaGb9mrBArt-ZIeu6s8w"]YouTube[/a]
[a href="https://www.artstation.com/rowye"]ArtStation[/a]
[a href="https://www.deviantart.com/rowye"]DeviantArt[/a]
[a href="https://www.behance.net/rogercreus9c71"]Behance[/a]
[a href="https://www.facebook.com/digitalrowye"]Facebook[/a]
[a href="https://twitter.com/roger_creus_art"]Twitter[/a]
[a href="https://makersplace.com/store/roger_creus_art/"]Makersplace[/a]
[a href="http://www.redbubble.com/people/rowye"]Prints and more[/a][/b]

[/center]