Image Swap

https://stackoverflow.com/questions/24622722/how-to-swap-an-image-with-an-existing-image-on-a-website-using-html

https://www.w3schools.com/js/js_htmldom_html.asp

Hypothetically, I'm looking for HTML-CSS-XML solution. XML is a markup language. I have used a different markup language on Reddit.

Initial searches brought up Javascript.  I've used copy copypasta Javascript on websites before but I've never studied it.