The image itself comes from the media folder:
<img alt="" src="https://beyondtellerrand.com/media/pages/photos/portraits-berlin-norman-posselt/2631825938-1578416643/cassie-evans-1600x1600.jpg">
I’m not familiar with how this is exactly implemented, but one way to achieve this is to make the images virtual pages.
Another way to achieve this would be via a route, in which you always return the same template, but with the image from the URL.