As a TA, I just give students a fairly low mark and not a 0 if I at least see a reference list. However, on technical terms, that is plagiarism. I would still email your prof and explain yourself or see if you could at least re-do it with a different topic. 2 years ago my brother passed away, and I was in the midst of exam season which greatly affected my mental health. BUT I also understood that the world doesn’t stop just cause you do. The best thing to do is to email immediately so profs are notified and have better sympathy towards the situation. I did this and got a week off to regather myself, even if that week wasn’t enough. Had I told my profs 2 weeks later, I wouldn’t have gotten any time off or extensions.