I Would recommend following up with your doctor. That redness seems to be a bit too excessive and you seem to have some small white pimples on the skin which generally is not normal. The best thing to do is see your doctor asap so that they can examine your scalp and determine whether it is normal or not.
You need to visit your hair specialist for a follow up care to make sure that your are healing properly.
21 days after surgery and have redness
The pink or red color is common in some people and may hold (unusual) for a few weeks after the surgery. If the redness bother you, you should go back to your doctor and ask about it. Make sure that the redness is not a sign of infection and your doctor will tell you that
It does not look normal for 21 days. You need an exam and a recheck with your doctor to make sure everything is OK. Photos do not substitute for an exam. It may be a sign of infection.
The picture is not very clear but looks a little strange. You may want to follow up with your doctor.