No, you couldn’t do it.

Once you change your number to a new one, the old number isn’t yours any longer and you have no control over it.

You can port your old number to an inexpensive VoIP service and have forwarding done from there, but that will close out your Koodo account and generate a final bill, including any tab charges.

Instead, consider keeping your plan as is and getting a new secondnumber from a VoIP service, and having that forwarded to your current phone.