It is your right to go to the police station to investigate and ask for a lawyer. You can do this, but in practice. I just want to tell you that it's hard.
Just like everyone upstairs said. China's legal system has no "right to silence".
If you must. Then the steps are as follows:
One: A lawyer should carry a power of attorney signed by you or your family. It's simple.
Two: you need to open a letter of introduction to the legal department of the superior public security organ branch of the police station. Otherwise, the police station will not accept it. It's hard to do.
After the two items are complete, the lawyer can go to the police station to provide you with legal advice and assistance.
But this is the hardest time. The police station will stop lawyers from intervening for various reasons. If the case is confidential, the lawyer's identity is questioned, or the competent leader is absent, etc., the case is basically finalized after the lawyer meets the suspect. It's no use.