Electroplating requires a much higher voltage than whatever these batteries would have put out. Apologies for the meme-y video, but Electroboom explains the issues quite well regardless:
So put a hundred more in series and you get bigger voltage. If 10 of them lit a LED, which needs something like 1.5V then 100 of them would give you 15V. Car batteries are 12V or 24V, depending on the car model/size, so 100 or 200 in series and you get that covered.
It's not even clear they were actually batteries. It's possible and plausible, but at the moment we have no way to confirm they were used as such, and may never do.
More information about these devices: http://www.ancient-wisdom.com/baghdadbatteries.htm