I have seen unity has built in grass foliage which you can choose the colour of, if this was built into unreal that would be awesome.
You can just use different materials for your foliage meshes, or do it like this: Foliage color variation - Rendering - Unreal Engine Forums
However, it would be a nice tool, but the information needed to be stored in some kind of colormap, so it would basically be the same thing, just easier to use.
yes but you still have to import the foliage in the first place. it should be an option when creating a project to add starter content + foliage or add it to the starter content