You would be amazed how much confusion there is going on in the photography world right now over lens sharpness. One of the biggest culprits is a company called DXO mark, which loves to publish lots of scientific looking data and then never publish how their numbers were produced or how to re-create their tests. For the most part I see it as nonsense (DXO mark that is). It does not help that there are some otherwise good and respectable Youtube Channels perpetuating DXO marks “perceived megapixel” scores, which attempt to summarize lens + camera combo sharpness into a single “mega pixel” like score, into a single number. That is like trying to explain the exquisite differences in case of a bacon cheese burger, with blue cheese and extra pickles with a single number. You just cannot do it, more so if you aren’t publishing how you are arriving to these numbers.
What we are seeing more and more of because of this, is that photographers are preparing to abandon otherwise perfectly good lenses, because they are under the impression they are not “sharp enough”.
This is my advice if you are not happy with your lens sharpness:
Stop it down. Most lenses are sharpest 1-2 stops down from being wide open and many lenses excel at f8. If you are shooting outside and have the light, and sharpness is so important to you as a shooter, this is the fastest, cheapest and most logical means to get sharper images.
If that is not enough for your purposes, then you should start looking for a new lens. (Ive been amazed by how many photographers do not know about the relationship of stopping down to sharpness)
Side Note: once you get in the f11 or f13, you will start running into diffraction issues, which is actually softer looking images. Yes, deep DOF will be there, but they won’t be as sharp.