Ca you get shiny pokemon out of eggs?

Well Magikarp isn't in eggs so at this point no. In the future I have no idea.

If you somehow manage to get an egg from months ago when they were still hatching out of eggs... maybe (at least it would be cool as research), otherwise No, Magikarp is not hatching from eggs anymore, so there's no way to currently "know" if eggs can pop out shiny magikarps.