Is the foundation of the main door kitchen 2O cm lower than the main room?

Not good. Although the low foundation of the kitchen can prevent water from spreading into the house, the whole house will look uncoordinated. If there are children walking carelessly, there will be bumps under their feet, even for adults. It is inevitable to stumble, which is very inconvenient, and from a Feng Shui perspective, the kitchen sinking lower than the main house will also affect wealth, so it is not good.