Hello, I have a x2 visa for 180 days and I am doing an internship,

Ale, I’m afraid it’s not easy for you to extend it for another 180 days because usually, if the internship will last for more than 3 months, you should apply for a work Z type to do it. So just to be secure, you’d better apply for a work Z type for the internship. The required documents for work Z type include the application form, a passport-style photo, your passport and its photocopy, an invitation letter issued by a duly authorized unit, and alien employment permit.