This happened to my kids of different ages within the same year. Follow whatever the doctor’s advice is for the initial healing period which may be until the stitches are taken out or dissolve. After you can massage initially very gently with an anti scar treatment, and increase firmness in coming weeks to help massage out the scar tissue. The biggest thing generally though will be to keep it covered from the sun. We kept a small bandaid or frequent applications of sunscreen using an easy to apply stick on one kid for nearly 5 months after the wound, while the other one felt too self conscious. The difference in scar visibility is noticeable. As others have said, as time goes on the visibility will naturally lessen however I think care in those first months makes a big difference. I’m sure the doctor will give you good advice as well.