Something I miss from Windows. When opening a dialog to post an image on some website I would often right click and open the image to check if it's what I wanted to share (since thumbnails are not enough sometimes). Right now the only option I see is opening the containing folder, which opens a new window, and it's fine, except if I start checking the images on that containing folder and then decide on an image to share, I have to find it again in the original dialog. KDE Plasma Version: 5.16.0
Sounds like you want to turn on the "preview panel" in the file dialog. Click on the "two sliders" button in the top-right corner and click "Show Preview Panel". This will show you a preview of the image you've selected or hovered over.
That's nice. But what if it's a high resolution image and i want to zoom it in to check some detail. The dialog has options to create new files, don't see why it can't have an option to open them. Just my two cents.