The fastest method to use icons is SVG Inline, but it is not the easiest !
* For using classic social icons into GP theme you can use this one (it seems you can also add custom svg icons with this plugin): https://wordpress.org/plugins/gp-social-share-svg/
* For custom svg icon anywhere, you need to “build” or to copy the <svg> inline code from Icons you need (from website/adobe/icon dedicated website suppliers) into a html bloc.
What I did to “simply” reuse svg inline is:
* Build a CPT custom post type called Icon
* Add a post per Icon
* Add thesvg inline code in a field
* Then you can call it using shortcode – get_field() function or/and you can use relationned field of ACF plugin
good luck =)
I’m novice, so wait for David he probably has a better idea !! 😀
That particular site is custom built and it uses images for its icons.
You could simply add your own images PNG’s or SVGs which would be best. To use SVG images in WordPress you need a plugin like Safe SVG or SVG Support.
The method that Sebastien mentions ( thanks Sebastien ) is the best way to go about creating your own icon library but requires knowledge of Custom Post Types and some PHP.