With the annotation command "Part/Workplane Geometry Styles" (part_layout_geo_styles) you can only select parts or workplanes. If you want to change the color of a sub assembly you have to select all parts recursively in this sub assembly. The command shows a very bad performance when it has to handle thousands of parts.
When a part is added to this sub assembly after this you have to apply the command to the new parts again.
The command should be improved so that it can handle assemblies in a performant way. Also added parts should show up with the correct modified sub assembly linetypes/colors automatically.