Adding values to rows in CSV
Indent the blocks properly.
Define the immutable exclusion lists before the loop.
To enhance readability, maintainability, and to avoid missing typos such as the dot after DODSCAN, which should be a comma, write just one array element per line without commas.




$excludedAccounts = @{
    unique = @(
        'ACCOUNTS - DODSCAN'
        'ACCOUNTS - Domain Admins'
        'ACCOUNTS - LADM_WS_Admins'
        'ACCOUNTS - Tech Enterprise'
    )
    account0 = @(
        'esrxadm1n_esi'
        '#Update'
        'medco_tech'
        'medco_admin'
    )
}

foreach ($row in $csv) {
    if ($row.Type0 -eq 'Domain') { 
        $newName = "$($row.Domain0) - $($row.Account0)" 
        $isRowExcluded = $newName -in $excludedAccounts.unique
    } else {
        $newName = "$($row.Netbios_name0) - $($row.Account0)"
        $isRowExcluded = $row.'Account0' -in $excludedAccounts.account0
    }
    $row.'Unique Account Name' = $newName
    $row.'Excluded' = [string]$isRowExcluded
}