You can add custom tags to the <head> of of your website that let you choose how the preview of the site on many services will be shown.
Simple add the following lines to the Integration tab of you Divi Options:
<meta property="og:title" content="This is my title" /> <meta property="og:image" content="https://any.green/wp-content/uploads/2020/06/cover_image.jpg" />
The recommended size for the image is 1200x627px and save it as a JPG.
You can get the link from any image that you upload by going to the Media Library, click the image, and find the Permalink in the bottom right corner.