Whether it works or not depends on how many samples are used to downscale. Amusingly, this attack was used for bait-and-switch and “click here to [x]” gimmicks on some websites, especially 4chan, and you can find examples tuned primarily for typical thumbnail generators (which, probably for performance reasons, tend to only sample a small number of pixels.)

https://thume.ca/projects/2012/11/14/magic-png-files/