"Medium" and "large" are multiples of examples and units of dishes.
In some places,' Zhong' is twice as much as' Example', and in some places it is 1.5 times. Generally 8- 10 people.
"Big" is three times as big as "Example", and some are twice as big. Usually used by more than a dozen people.
Be sure to ask the waiter when choosing.
This is what I learned when I was working in the south. I don't know if you can understand.