What If? All settlements all over the world are turned into Underground Vaults/Arcologies/Megacities?

[CarlManvers2019]

All powered by advanced geothermal energies and nuclear power with artificial sunlight and the technology to create artificial food and tech for easy-online-education

How does the world react in the longterm?

They can "go up" and go to other "settlements" via a massive underground "road/train network" even a continent away