@heinelg Jetpack Social already has a default format when sharing posts to Facebook. You can use the Social Previews extension to preview what the post will look like when shared on Facebook, as described here: https://jetpack.com/support/jetpack-social/extension-social-previews/
If you want to change that default format, you can adjust the sharing settings on an individual post. This guide explains how to do that: https://jetpack.com/support/jetpack-social/social-sharing-new-posts/
If you need more help with that, please post your site URL here so that we can have a look, and give us more details about what you’re trying to achieve.
If you want it to remain private, you can also contact us via this contact form. If you choose to reach out directly, please include a link to this thread.
Thanks!