Do you mean the auto reply part (msg) should be 10 lines instead of one line?
If yes, you can use HTML codes like <br> to insert a link break.
For example:
$msg = "<html><p>Thank you for you email.<br>If you still need aaitional assistance:<br>.XXXXXXXX<br>.XXXXXXXXX<br>.XXXXXXXXX<br>.XXXXXXXXX<br></p></html>"
Set-MailboxAutoReplyConfiguration -Identity ug1@contoso.com -AutoReplyState Enabled -InternalMessage $msg -ExternalMessage $msg
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