9 h layover in YYZ arriving from the US and then departing international
Can you clarify your nationality? Most visas issued by Canada are required prior to arrival.
Typical intl to intl connection in YYZ has baggage tagged through to final destination. You head towards the customs area but then take a quick left, go through a CBSA documents check and go back on the international departures side.
You can have your baggage short tagged to YYZ, in which case you claim it prior to leaving the main customs area and entering Canada. Then you would need to recheck your bag.