Yes, if you want to have valid certificates for markets all over the world, your certification body must be accredited by IAF. Otherwise, it may happen that you will not be able to enter a certain market because your certification body will not be recognized.
We have prepared the template for Technical documentation that is requested in Annex II of the MDR 2017/745. This document is much broader than is requested by ISO 13485:2016 but can be a guide if necessary.
The question here is are you a manufacturer, distributor, or some other business entity? If you are a manufacturer, for the EU market, your medical device file must be totally in compliance with the Annex II and Annex III of the MDR 2017/745. If you are a distributor or some other business entity then it is enough to have in the Medical device file what is written in the standard.