What can I do about this terrible scar from a strip hair transplant?

The best treatment for scalp scars is Scalp MicroPigmentation. I have extensively published on this technique and on the website you can see many examples of patients who had this done for scars of all types. Below is a typical example of a patient who had a scalp scar treated with Scalp Micropigmentation and you can see more examples of this here: https://scalpmicropigmentation.com/scar-covering/