Yes there will be roaming fees for sending SMS from the US to Canada unless you have a plan that includes it. SMS text uses the cellular network and does not use WiFi. There are other messaging systems, like any of the popular social network platforms, that uses whatever Internet connection your device is on so those will use WiFi if that's how your device is connected. Those will also incur roaming data costs if your device is not connected to WiFi.
See this for travel options:
https://www.telus.com/en/mobility/travel
