Lots of options:
1) Official airport parking - details at
https://www.torontopearson.com/en/transportation-and-parking/parking
2) There's no shortage of off-site parking lots with shuttles to the terminals. A google search will provide you with lots of options
3) Hotels. There's many hotels that, if you stay the night before your flight, will allow you to park your car for free while you're away and shuttle you to the terminal. Again, tons of options for this.
On top of that you can also take the UPExpress train instead of parking at the actual airport.