Can I upload example files to the knowledge during creating custom GPTs?

As Title , can I upload the examples files to Knowledge when building customs GPTs?

The File of examples only include “User_input_text” and “GPTs_Output”

As for the file type , I can use JSON , XML , CSV docs.

Or Is it okay to use Few-Shot method to write them down?

Yes you can.
I uploaded an example file to knowledge and it works without problems.