Using the inexpensive Sony FE 50mm f1.8 @ f2.0, this is a 100% detail from a photograph I took of my daughter.
Created for a yoga class she was teaching, it was shot at ISO 640 and was intended for web-only viewing, although for these purposes ISO 100 would have been much better.
An aperture of f2.0 was used to blur the background. Slightly cropped, most of that frame is depicted in the B&W insert. This illustrates central sharpness similar to wide open but unfortunately you can only see fine detail in the hairs.
Experience shows that at f5.6-f8.0 the farthest corners would be notably better than this central area and of course the center would be correspondingly better yet.
This is consistent with my artificial testing and image-wise this lens is optically excellent stopped down.