Space ships are divided into classes. For example, then “Soyuz-MS”, American Crew Dragon and the Chinese “Shenzhou” is the orbital ships, designed for transporting crews from the Earth to the space station and back. Any serious maneuvers in space, they will not.
New Chinese ship belongs to a completely different class of vehicles — lunar. He is able to go into lunar orbit and then return with her to Earth. This requires to work is a very big boost, at least 1500-1600 meters / second. That requires a lot of fuel reserves, and the ship needs to be designed with this in mind.
For example, to these ships belonged to Apollo, where the Americans flew to the moon. Look at its layout. It is clearly seen that the tanks occupy a significant part of the ship.