Is my domain's login address the same as exchange mail?

[frak105]

I imported 100 users from Windows Server 2019 using Azure AD connect. Each user logs in 2 letters of the name and two letters of the name for example.
John Brawo has the login brjo@mydomain.com

Each user should have an email starting with the first letter of the first name, dot, and full name for example
John Brawo has the email j.brawo@mydomain.com

How do I configure exchange mail?

[#2]

you can change UPN in you AD and sync the changes and then assign licenses, you should then have same UPN and email address.

[#3]

And what to do with the identifier? The user logs on to the computer
brjo@mydomain.com
the same user has an email address
j.brawo@mydomain.com

Now I'm transferring all email addresses to Office365. Using Azure AD connect in office 365, I have other employee email addresses
brjo@mydomain.com
Can I import users with a login
brjomydomain.com so that they have the address j.brawo@mydomain.com?