Thanks Sam. Seeing some examples gives the request some context I was incapable of imagining before.
I like the idea of using spoiler tags since having it “per post” is less of a “nuclear option”. But only if blurred is enough. eg.
[spoiler]
<img src="//cdck-file-uploads-global.s3.dualstack.us-west-2.amazonaws.com/meta/original/3X/4/d/4d01eca87294cf4ca00fed7124a93674e54169cc.png" width="336" height="210">
[/spoiler]
So perhaps a plugin that adds a way to toggle
div.topic-body img {
display: none;
}
or something else would be better.