Hello, I am looking for information about X2 visa

Alejandra, if your internship in PRC will last for a long time, I’m afraid you should apply for a work Z type to do it.
If you want to extend the X2 type, you need to get the relevant documents from the school. You need to provide admission notice or certification documents of enrollment issued by the school as well as your passport, the application form, a photo, and valid registration form of temporary residence.