That feature doesn't exist yet.
But there are some considerations to be made in implementing this.
Like the images that shouldn't load, do we hide them, do show a black shade or placeholder. If so which placeholder because i doubt that you want to see Jerboa icons everywhere instead. If we hide them there there is no difference between postviewmode largecard shortcard so do we keep showing both? Someplaces it's probably better to hide them like the avatar.
This will most likely be part of a much bigger "data saving" feature where you can enable loading images(previews/comments/avatars/banners) on WiFi only/all/never.
And it be pretty cool if you could granular select which images you do and don't want to load. But there is no UI for that yet. So that will have to be designed too.