You can't apply for a work visa before you get a job in China becasue some required documents are provided by employers, such as
An invitation letter from the relevant department of the Chinese Government or Government-authorized company.

Original Foreign Experts Working Permit issued by the State Administration of Foreign Experts Affaris, or orginal and copy of Alien Employment Lisense issued by the Ministry of Labour amd Social Security, or other relevant permit of employment.

If you use a visa agent, they may help you get a work vsia (residence permit) before you get a job. You can change your work vsia under your employer after you get a job.

Good luck to you!

Best regards,
Maggie
MSN/email: hotmail.com|maggielee66