I have an Air Canada (Sky Regional) Aeroplan X class flight booked next week. Can same day earlier flights between YYZ/YOW be taken free (subject to availability) and arranged at the airport counter?

i recall when I flew from SYD-SFO-YYZ once on aeroplan, the SFO-YYZ portion was Air Canada and I arrived earlier from Sydney than planned. I simply paid a fee at the AC counter...$100 bucks or something...and they moved me to the earlier SFO-YYZ AC flight without Having to deal with any Aeroplan call centre shenanigans. Hoping I can do something similar in Ottawa and I know the same day airport change fee is zero for tor/ott flights.