Following another booru's example, I copied the name they use for the tag some people on Danbooru have been struggling to make a name for. Juxtaposition is the present name.
Present wiki:
Posts where within the medium, a photo or recording of a character physically present is portrayed with contrast to eachother. A common example is someone portrayed in a photo or recording having sex, while the physically present character is portrayed acting dignified or normal.
However, this was a rushed decision on my part. I was so eager to get it tagged at all that I jumped straight to it five minutes after no input from my suggestion in Discord.
It has been advised the name be changed to more accurately convey the intent. I don't agree 100% with the proposal for juxtaposed_inset, as inset's use presently implies an additional image must be present in the image. But, this is not always the case for the intended use.
Inset's wiki:
Pictures having other pictures (predominantly photos/portraits of characters) set into the main image.
Let's say a post has a large sign with the words "The shining beacon in a brave new world" but the rest of the scene is a hopeless wasteland. This would indicate juxtaposition without an inset/another picture in the main image.