It sounds like you're looking for a link preview that includes an except and a featured thumbnail image. That's not supported in Lemmy.
If you want to link directly to the image (aka hot linking), you need to grab the image URL and then link to that rather than the full article.
Note that while hot linking like that usually works, it's often frowned upon unless the original site is specifically set up to handle it - a good example of a site for image sharing is Imgur. Here's a good explanation:
https://awesomelytechie.com/dont-hotlink/