The double domes are common, and I've seen 3-4 bulb hoods that have the bulbs horizontal, but has anyone ever seen a fixture/dome that holds more than 2 bulbs vertically thats available/for sale anywhere?
I have never seen more than the double.
If you can't find it Mr Detective, it doesn't exist. Lol
With some modifications, you possibly could rig a ceiling light of similar style. Most can be changed from hardwired to plug in.
I know at least 1 exists, easy enough to add another socket to some of the larger double domes; I was just curious if there were any made/sold by a company.