Show image preview for page link? None showing

Even if I add a featured image to a site page, there is no site preview image no matter which social media site I drop it on, and I want an image preview of the first shown image to increase views (and not my site title, in case it defaults to that). For example, the portrait on this link should show if I paste the link on Facebook: https://agentrosehq.com/aib-chapter-2-1/

How do I add this? I'd rather not use the featured image function fyi, since it isn't the best format for me.

Thanks!