Ifranview almost does this- you can make GIF's decently big in normal viewing mode but when you go fullscreen mode the GIF's become small again. If I'm not mistaken, ifranview considers this a "feature" which it is in some cases but not my case. You know my use case, fellow men.
I also tried 123image viewer on the windows store, but it doesn't seem to have a good fullscreen mode for gifs
