Iif I link an image directly from my own site, which I tend to do, it will only be resized by the Forums Image Handling functions and nothing else.
As below:
Overlooking Marton in Westemnet, Rohan
Sunset shot of Stangard in Eorlsmead - Great River
Both these images will re-size as you re-size the browser view up to maximum resolution of 3840 x 2160