If you are the applicant of the DA and it was lodged via the Planning Portal, you can access all your documents via the NSW Planning Portal.
If you engaged a third party (Private Certifier/Architect/Planning Consultant etc) to process your DA or other applications, you can liaise with them to provide all the documents.
You can access the Notice of Determinations (Consent/Approval or Refused) for Development Applications (DAs) and Modification DAs via the DA Tracker.
Plans are not shared on the DA Tracker for privacy reasons. So, if you want a copy of these for your property they can be requested via a GIPA. If the applicant is not the owner of the plans (i.e. builder, drafts person or architect) you will need to obtain proof of owners consent for the plans.