seized documents are not automatically sent back to the applicant, more often than not you have to request them and each IRCC office has a different process. It mostly entails emailing the office that seized your document and requesting it back, they'll give you an appointment etc.
Instruction are in different threads in this forum.
* As others have noted, if you use your seized documents for travel or renew them you are putting your status at risk- look up cessation/re-availment
