I think 4-pin is the standard, at least on newer vehicles. I’ve seen 5-pins on my uncle’s old farm Dodge. That thing has gone through Hell and back and still runs like a top, and I’m not a fan of Dodge by any stretch. Oldies still hold together better than the new stuff.
Not sure about 5 pin flat.
4 pin and 7 pin are the most common, at least in US