If you mean on threads, then you first need to save an image from the destination, after you've done that, click upload a file: - After you've done that, an option should appear at the bottom like this:
- You can either pick thumbnail or full image, the difference is that thumbnail option is a lot smaller when displayed, whereas 'full image' shows the proper size.
I hope this helped, please message me or another staff member if you have any more regards to this!