This gist will help programatically replace the from name and the from address on New Lead Notification emails.

functions.php

<?php //remove me

add_filter('inbound_email_response/headers' , 'modify_lead_notification_headers' , 10 , 1 );

function modify_lead_notification_headers( $headers ) {
    $old_from_email = '[email protected]';
    $new_from_email = '[email protected]';
    $old_from_name = 'The Site Name';
    $new_from_name = 'The New Name';
    
    $headers = str_replace( $old_from_email , $new_from_email ,$headers);
    $headers = str_replace( $old_from_name , $new_from_name ,$headers);
    
    return $headers;
}