Ethically, I am against any form of prostitution or soliciting it, as many women are trafficked in the process.
From a legal standpoint: Block him immediately. If he tries to contact you, keep recordings of any calls / screenshot of messages and report the situation to the police. They may not dive into details but will be able to trace the matter, but that is the last resort. 99% of time, they won’t bother calling you post blocking.