url like this? I typed 
I don't know completely what you mean. I'm on kbin, so currently for me it shows a blue link "image" but it doesn't seem to do anything when I click it. Wonder if it looks different on lemmy
maybe kbin is too young to be able to do what you're describing? I'll put a screenshot of what I can see (desktop for kbin.social) screenshothttps://imgur.com/a/g3dJUyy
(btw will you type exactly the command you put, maybe with the code `` option)?
Alright so I went on lemmy cuz I'm using both xD and I can finally see what you meant in your earlier comment. You said do  right? eg.  image
and I'll give postimages a go :) I just used imgur since I knew about it
from what i understand, this is syntax implemented on lemmy. it's not from the deeper ActivtyPub protocol all of these things are implementing. If that's true, it won't render on kbin how it does on lemmy.
seems to work fine on viewing the image embedded on kbin for me.. it doesnt expand automatically (u gotta click a little expand button to show it) but that may be a setting only somewhere on the site