I have a 23-hour-long layover in Toronto, Canada.
Am I entitled to board and lodging from the airline?
In general, no. If you book a ticket that includes some time in a city along the way, it's up to you to figure out where to sleep and to pay for that.
Two exceptions. First, if you had a short connection, say two hours, and there's a problem that delays the second flight and you have to spend the night there, the airline might (might!) pay for a hotel.
Second, Air Canada (since you mentioned Toronto) has a special program involving connecting through Toronto, Montreal, or Vancouver and getting a hotel night as part of a package. (Free if you are on a high fare, $49 otherwise.) You also get lounge access at the stopover airport. It's pretty enticing for someone in your situation.
Just don't assume that the same practice applies to any stopover you might book, on any airline, anywhere in the world.
No, you're not entitled to anything that's due to the scheduling of your flights prior to entering the contract.
Were the airline to change the schedule later, say due to weather conditions, technical problems, etc. you MAY be entitled to compensation based on local laws, international treaties (not relevant on internal flights), and airline policies (which would be reflected in the terms of your contract).
But as you booked your ticket knowing there'd be a 23 hour layover, how to deal with that is your responsibility and yours alone. You can of course see if the airline has options to add a discounted hotel for the night, they might have such offers.
China Southern Airlines offers a free hotel stay for a long layover. I learned this when a gate agent approached me upon arrival and made the offer for a hotel in Guangzho China during a 15 hour layover. Since then I've learned that other airlines offer something similar if the layover is long enough and all the travel is with the same carrier. Ask.
It's called STPC (Stop over paid by Carrier). Some airlines do this if the layover is longer than X hours. I know for a fact that Emirates does this if the layover at their hub in Dubai is longer than 8-9 hours. They take care of the hotel and the formalities for getting you out of the airport to the hotel(in some cases Visas and such). It is better to call the airline call center and ask whether they provide STPC. Hope it helps.
Many airlines do not do this practice; however, in many airports, such as in Kuala Lumpur (Malaysia) and Singapore airports, there is a hotel that rents rooms at 6 hour intervals at very good rates.
Many large airports have rest areas, shops, restaurants/cafes and are like mini-cities in themselves - so there is plenty to do, but it is always a good idea to book any in-airport accommodation ahead of travel. Smaller airports would not have these facilities. In any case, as Kate Gregory said, it is the responsibility of the passenger to organise how you spend your layover.