Thank you so much for replying.
I got the graduation letter on June 19. My study permit officially expires in 2021, but it’s only valid 90 days after graduation. I applied on day 90 (September 17) but because the timing of the website, the application was received on the 18th (day 91).
If they reject my application and the 180 days are over, what are my options to remain in Canada?
https://www.canada.ca/en/immigration-refugees-citizenship/services/study-canada/study-permit.html
According to this link, the 90 days is counted from the day you are first notified that you have graduated and not the day you received the graduation letter. I received my graduation letter on Aug 31st, but it mentions a Status date of Aug 21st. That's the day I received my final grades, and the 90 days count started for me from Aug 22nd, the next day.
You should check your graduation letter to see if there is anything mentioned in your graduation letter and count the 90 days accordingly. You could have been well over the 90-day mark (and out of status) when you applied for the PGWP.
I have no real answer to your question about your options to remain in Canada if, God forbid, your PGWP gets rejected. I am not sure what your profile is, but some of the possible things you could do to stay/come back to Canada are:
1. Apply for express entry
2. Take a second course, get a study permit and then apply for a PGWP. PGWP can only be issued to a person once in a lifetime. So I think a person will still be eligible for a PGWP if they did not receive it for their first course. Talk to an immigration lawyer and/or IRCC to confirm if you will be eligible if this is possible.
I want to end it by saying that Canada is a forgiving nation, even immigration-wise. Especially if you tell the truth and own up to your mistakes. I am speaking from personal experience. I hope this gives you peace of mind.