Just out of curiosity: Is there a filter that resembles a Roy Lichtenstein, see, e.g. Roy Lichtenstein - Wikipedia. Thanks.
Moinchen, Helmut!
Search for
Lichtenstein Gimp
on duckduckgo, and you will
find some suggestions.
MfG
Claes in Lund, Schweden
I don’t think so.
There are some filters for color quantization and halftoning, but I’m not sure how to use them to get something close.
Getting a good Lichtenstein effect is mostly manual work - you need a really bold outline with closed areas, then you can fill those in with patterns. Most associate Lichtenstein just with rasterization, but there is much more to it. He used a lot of screen printing but mixed up the techniques how each screen was created. From flat colors to patterns to rasterization dots.
I doubt anything but a specially trained machine learning algo does have a decent chance of getting a plausible result.
Not G’MIC, but the Newsprint GIMP plugin (under distorts) does sort of an alright job with Lichtenstein like result if you choose dot and CMYK. Below’s link to a tribute I recently did for Bob Barker. 
https://www.flickr.com/photos/163034485@N03/53147220243/sizes/o