There is, search for "test patterns" on Netflix: https://i.imgur.com/nOb7BX4.png
It showed how the extension presents info like resolution, both a/v bitrate, total throughput, and more.
I used to use this extension to force a bitrate, but Netflix removed the ability. Was super useful when you were stuck watching 144p and Netflix refused to serve you anything better despite your connection improving.
So -- assuming the input device isn't compressing and then upscaling, which a Chromecast wouldn't -- it's easy to see the resolution, for Chromecast, XBox, whatever.