If it was something is simple as just automatically seeing the contents of the textarea, it could be done with custom JS in the ACP.
Small images preview in topic
Hello! I need to post many images in post (for example 100px width) and on click enlarge to full size (for example in popup frame). I'm try nodebb-plugin-image-sizer (but it not comptiable with latest version of NodeBB).
How plugin I can use for change image size in post?