that’s totally possible. but you cannot directly use GIS coordinate systems inside Unreal. the trick is to have a geo-ref’ed calibration point (maybe QR marker at a wall somewhere) which the AR device detects and which anchors the AR scene in the real world. you then use a suitable projected coordinate system in CityEngine and map the center of the scene (or some other virtual point) to the anchor/calibration point.
best,
simon