Yes heads are cast then cnc cut to spec for valve cover and bolt holes. But most of the time they are not considered to be cnc unless they are cnc ported or cnc combustion chambers.
My procomps have cnc combustion chambers but the ports are as cast for the most part. CNC port work is a lot of money over the price of the head. but if your buying heads you can just buy the bigger ones and save the buck the cnc would have cost. Yeah its a little better but not worth the cost unless max effort racing. My procomps setup and ready to bolt on with 210cc intakes and 2.02 valves were 600 a set. Not 500 for a single head. If they flow a little less its ok I got the big ones anyway so still should be good. Exhuast ports do not look to be restrictive they seem open and well designed. But they have not been on a bench.
So yeah heads are made with cnc already. Larger production run heads are made with a single stage process. where the holes are drilled and tapped with the same machine all at once. it is not really cnc. But close enough they are made by computer/human on a machine.