6 hour layover in Toronto

Well, IF your flight arrives on time or early, and IF you don't need to spend a lot of time going through customs and immigration, then I suggest you take the UP Express (train) to Union Station and then take the subway up to the Yorkville area from there. This would take you at least 40 minutes each way.

https://torontolife.com/food/10-best-restaurants-yorkville-now/

Or you could stick to the area right around Union Station: https://www.tourbytransit.com/toronto/dining/restaurants-near-Union-Station, which would cut about 15 minutes or so off the trip each way.

https://torontolife.com/food/downtown-toronto-best-restaurants/

Whether you are arriving at Pearson on a domestic or international flight, and connecting to a domestic or international flight will determine how much time you would have to leave the airport. If arriving and leaving on a domestic flight then you could squeak out a lunch downtown. Figure an hour from deplaning to get to Union Station by train ($12.35 CDN one way). Returning, 40 min or so from Union Station to Pearson and allowing 2 hours if flying domestically for check in and security. That leaves you about 2 hours in town.

If arriving and leaving internationally, you won't have time. You would need to go through Immigration before leaving the airport, which could easily take an extra 30 min if they are busy, and would need to be back at Pearson 3 hours before your flight. That gives you half an hour to an hour to grab a sandwich somewhere near the station. All in all, I'd see if you can access on of the lounges at the airport and just relax.

Your message doesn't say where you are connecting to, but if your onward flight is to the United States, you go through U.S. immigration and customs in Toronto airport rather than on arrival in U.S., so you would need to allow time for that as well as the normal airport security process.

Thank you all. You’ve likely spared me and my family from making a bad mistake.

We are coming from the US and heading to Quebec City on our second flight.

I just hate to spend all that time in an airport with a new city, for me, right outside.

Just going to add in, I agree you don't probably have time with 6 hours. If you had a bit more time, instead of taking the train all the way to union, get off at Bloor station. From there you have nice neighbourhoods to walk, High Park, and some good restaurants. But your connections would all have to be perfect to make that work.

Returning to the US through Pearson, take care to go to the correct area for US border entry. It's a busy airport and there are signs and a fair number of airport staff to point the way.