True, there is a huge variety of sizes of rice cooker, depending on how much they make and how fancy they are

The rice cooker I have is cheap, simple and small, makes enough for at least four people and is the size of a 1.5 qt pot, about 9” in diameter. It has one button and consistently cooks decent rice in 15-20 minutes

• www.amazon.com/…/B00N9N6GOY

I guess microwave ovens are all sizes as well: mine has got to be 30” across by 15” deep