China has 1.4 billion people. The government could care less if you leave and don’t come back.
That was a flip answer. Chinese citizens are allowed to emigrate to other countries. The government has tried hard to lure back those emmigrants who have valuable technical and business skills.
China is not the police state that it was under Mao. There are still some totalitarian aspects, but this country is unrecognizeable from even a decade ago.