Full mailbox permission Office 365

I have recently been utilizing MigrationWiz https://www.migrationwiz.com/ for some of my Office 365 migrations.  The easiest way to do this is my utilizing an admin account – both on your Exchange on-premise or 3rd party hosted solution & on Office 365.  In order to this, simply connect via Powershell and ran the following commands:

$LiveCred = Get-Credential
$Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri https://ps.outlook.com/powershell/ -Credential $LiveCred -Authentication Basic -AllowRedirection
Import-PSSession $Session

Get-Mailbox -ResultSize Unlimited | Add-MailboxPermission -AccessRights FullAccess -Automapping $false -User exchangemailbox@thatwillhavefullaccess.com