You may be looking to include someone on your own team, such as your manager, an Account Executive/Account Manager, or perhaps even a group of prospects on Flow emails.
Once you Cc someone on a Flow email, that Cc'ed recipient will automatically be added to the rest of that Flow's emails, that are being sent to your imported contact/lead. You can remove a Cc'ed recipient from future emails in the Flow if you'd like to do so!
In the example above, Jack Rogers is the original contact imported to the Flow. Ralph from my own team is Cc'ed on this email thread, as well as Sarah Johnson from Jack's company. In this case, both of them will be Cc'ed on all emails to Jack Rogers in this Flow only.
To remove them from being Cc'ed on this email and the rest of the emails in this Flow, simply click the 'x' to the right of their email address.