Yes, two industrial zone buildings (factory and power plant) have 6-tile regional effects, as do two entertainment district buildings (zoo and stadium). That GE will expand the default radius from 6 tiles to 9 tiles for whatever district you put him in (but just for buildings in taht spdcific district.
Scan around your cities and see which industrial district (that's usually the right choice) will give you the most bang for his charge, given city spacing.