Hey there, stepping-stone,
Thanks for taking the time to join us here in the QuickBooks Community. At this time, the feature to automatically add late fees to invoices isn't available in the Canadian version of QuickBooks Online. However, you have the option to manually add service fees to invoices by following the steps listed in this article.
I can see how being able to automatically add late fees would be something you'd like to see, so I encourage you to leave feedback for our developers. Comments are viewed and considered as they create new features and updates for the software.
If you have any other questions, feel free to reach back out.