In August 2018, my neck was terribly disfigured by hematoma/scar tissue (it is soft tissue). What should be done? (photo)

First- It would be helpful to know the cause of hematoma in this area. Based on limited photos- a full check and neck lift separating all of the retracted and swollen areas - will be helpful. It may not be completely corrected but should be noticeable better - in the right hands

Thank you for sharing your excellent question.  Yes, most likely this can be improved but will require an additional surgery.  Seek out a series of providers to discuss your concerns and to evaluate your candidacy.