With SIN renewal, you can ask to have that expiry date changed. To change the expiry date, you have to show a valid documents, like the ones you showed when you first applied for a SIN. You can do this at a Service Canada office.
How to Renew your Social Insurance Number (SIN)
Once the expiry date on your SIN has passed you have to visit a Service Canada office in order to ask if the date can be extended. This is reliant on the fact that your planning to stay in Canada and if you have the needed documents to prove your status in the country. This is referred to as ‘implied status’ which is the title given until a decision is rendered by the IRCC, this status means you may be allowed to work even though your SIN is expired.
As soon as a decision has been made by the IRCC permitting you to continue working in Canada, you must update your SIN records with the new expiry date by taking your new immigration document to Service Canada.