We made this simple with the website editor, have you seen sites with preview images and icons in browsers? We have this setup as 2 things you can upload directly from the panel to make your links look like this.
First step is on the panel when looking at the sites at the top of the sidebar you will see this.
The middle image is the site icon we show to browsers and the background is the image that we use for social media, we also use the images in some themes as icons and background photos. To change click on
Update image/icon and
Update Photo to upload new images, updates are reflected as soon as you reload the info page or open the site editor.
Let's now add the site to our bookmarks and post on social media to see how it looks.