I know how to reduce a collection to one image, or an image to a value in Google Earth Engine. But I can not find an easy way to reduce each image in a collection to a statistics and get a list of that. How it can be done?

As it is easy to get a list of a metadata property over a collection, I was thinking that maybe I can just add my statistics as a metadata to each image, but I couldn't find any way to add a property to the image. Also even if I can, then maybe I can not apply it over collection because the output is not a map.

Any help?