Is it possible to have more control of the layout and placement of the images so that for example no ugly vertical sidebars appear as in the first article or else selecting a different layout for the position of the image relative to thtextbox ? Long question, maybe short answer (“no”?).
You just need a slightly bigger image for that specific post. This one is to small to cover the whole area. Changing the layout won’t help and it’s also not really possible without changing the whole structure.