Placeholder Dummy Image in Image

[Fabian_Weller]

Does anyone know a webservice that can give me Placeholder images that look like this:

Image in Image.
I tried it with https://pickadummy.com/ where I can set a Border. But this is not working, because the ratio of the two images should stay the same.

I want to use it as for the Background image in XY column. Since SVG is not supported for that.