Resizing small icons slightly larger usually doesn't produce good results, since there's so little data to build from.
There is Internal, Small Icons for Context Menus which gives smaller versions of the internal icons that match the system icon size. Reducing size works a bit better than enlarging, but is still imperfect if scaling is required. (Scaling isn't always required: At 200% DPI, we can use our 32x32 icons which match the system icon size already.)