Does fizz provide a free email address? if yes what will be the domain(@fizz.ca or @videotron.ca)?

no, fizz does not provides any emails

This is why you should use something like: Gmail this way you can move to any provider anytime
once you cancel with Videotron your email will be canceled so you will lose it.
you should keep Videotron for a month or two create a gmail account once an email comes in you should advise them of your new email.

Fizz does not offer email domain.

You do have a lot of free email accounts to choose from.

Best free email accounts: https://blog.hubspot.com/marketing/free-email-accounts

No emails.

No they don’t