There are two possible solution for this one.
One is the scalp reduction surgery and the other is hair transplant.
For scalp reduction surgery, this procedure would reduce the forehead space creating a fuller head of hair. But this would really depend on the surgeon’s assessment. Hair transplant on the other hand, used Follicular Unit Extraction (FUE) to reduce forehead size, hair grafts are individually removed from the donor area to the area needed to be covered. Usually, some doctor suggest both procedures.
Hope this helps.