Take photos (full-length, half-length, artistic photos, if you have been a model before, take model photos), go to companies such as cultural development and cultural communication, tell them when they can participate, and then leave a message. They will contact you if they have a suitable case.
You can also try to go directly to the modeling agency, but they usually have to work full-time.
If you are a girl, you must pay attention to safety. It is best to go together for the first time.