Yes, you can buy a lens that can do both, but like all things, compromises will be made. That said, no, the 50 1.8 is not a Macro lens. Canon does make a 50mm 2.5 macro, but it wouldn’t be my recommendation.
A macro lens is a specific type of lens that can focus very close to the object; technically a true macro can provide 1:1 magnification. Many general zooms will say macro but are not are not truly 1:1. True macro lenses are quite spectacular, in my opinion, it’ll blow you away when you see how sharp they can be.
Portrait lenses on the other hand usually have a large aperture (less than 2.8). This allows you to isolate your subject from the background, usually provides a softer look that works for portraiture, and allows more work with natural light. People pay a lot of money for pleasing bokeh, a very subjective consideration.
Long story short, I’d look at the Canon 60 mm 2.8 Macro, or the Canon 100 mm 2.8 Macro. I prefer the 100 mm for macro work (it’s a fantastic lens), but it’s a bit long for portraits on a crop camera… but can be done if you have the space. I do find the lens too sharp for portraits, but that can be fixed in post.
