At the company were I worked we had a name change. They also use the display name in outlook to send mail. Example: Daag van der Meer [Company] So everyone see direct what the company is.

The script below built the display name with firstname lastname [Company]

# Script created by Daag van der Meer
# Blog.van-daag.nl

Import-Module ActiveDirectory

#creates a list of all users (change all between <>
$allUsers = Get-ADUser -Filter * -SearchBase 'ou=Users,ou=<OU>,DC=<DC>,DC=<DC' -Properties cn,displayName

 
# Add your company name or something else after username 
$hi = "<company>"

 

foreach ( $u in $allUsers | Where-Object { ($_.givenName) -and ($_.surName) } ) {

    $fn = $u.givenName.Trim()

    $ln = $u.surName.Trim()

   

    Write-Host $fn $ln

    Set-ADUser -Identity $u -DisplayName "$fn $ln $hi" -GivenName "$fn" -SurName "$ln"-PassThru |

        Rename-ADObject -NewName "$fn $ln $hi"

}