You’re almost never ever going to get each and every tiny little stray hair detail perfectly in portrait mode. You can not compare something done with optics vs something done in software. Optics will always win.
Here’s an example I took with a 5d Mark IV and a 85mm f/1.2 (@ f/1.2)
View attachment 725725
A real lens will get that super fine detail of stray hairs (whiskers in this case) because it’s optically done, it can resolve that kind of detail, it doesn’t rely on masking to blur, it relies on physics of a lens, focal plains, distance to subject and aperture. iOS portrait mode doesn’t. It’s taking a best guess to mimmick it.