The Font Awesome icon shortcode has 3 options:
Icon: Choose the icon
Example: [icon type="fas fa-cog"]
Href: Add a URL to the icon
Example: [icon href="URL"]
Target: Link the button to a new window, or not. To link in the same use _self or new _blank window
Example: [icon target="_self"]
On the Font Awesome website you can see all available font classes you can use.