First, remember that ChatGPT is collating information from good and BAD sources so it's not yet considered a CRAAP or reliable source. But if you use ChatGPT, it must be cited much like any other source.
Secondly, anything in your essay, reflection, portfolio, report, IA, P2 or EE, that is not your own must be cited. Any AI, including ChatGPT, is considered a research tool NOT a writing tool. The assumption for any piece of work that you hand in is that it is yours, using any AI to write for you and then saying it is your work is a LIE. Simple as.
Finally, the IB has samples of your written work from your exams and from other work you submitted and can identify if the work produced is not your own through their own algorithm.
If you have any more questions, come to the Library and chat.