Can tenants change the store door privately?

At the level of laws and regulations, this is unacceptable. It is illegal to expand the gate without permission.

If it is your own self-built house, it should be no big deal. If it is a residential commercial house, it will not work, because the facade belongs to the public and all the owners. If the owner expands the gate privately, it will not only affect the beauty of the whole building, but also let other owners follow suit. If the circumstances are serious, you can also accept the punishment of urban management law enforcement departments.