My App Store account was set up in Canada, now all my Canadian credit cards are expired because I live somewhere else. I can’t change the region or pay using my new credit cards. I need to update my apps and download new apps

Change your Apple ID country or region - Apple Support

You will have to have a valid payment method for the country to which you are changing stores.

Payment methods that you can use with your Apple ID - Apple Support

You could pay the overdue amount using a gift card from the country with the balance owning (Canada). Get a friend back there to buy one for you? Of course then you'd probably have excess balance in your account which you would either have to spend and/or ask Apple to remove and keep.

PayPal is an accepted payment method in some countries but I don't know the details of how it works. It would not surprise me if Apple had some feature in there to test the country of origin of the payment to PayPal, otherwise it would be highly abused by people wanting to change countries to buy things not available in their own country's store.

You can contact Apple and ask them if they have a different solution:

Click here --> https://support.apple.com/choose-country-region Select your country, then a product. If you don't see one that handles your issue then keep experimenting with selections until you reach one that gets you a chat session or a telephone call and get the representative to redirect you.

or:

Contact Apple for support and service --> "See a list of Apple phone numbers around the world."

Click here --> https://support.apple.com/HT201232