Use a custom logo size for the email templates addon for Restaurant Reservations.

email-templates-for-rtb-logo-size.php

<?php
/**
 * Plugin Name: Custom Logo Size for Email Templates for Restaurant Reservations
 * Plugin URI: http://themeofthecrop.com
 * Description: Use a custom logo size for the email templates addon for Restaurant Reservations.
 * Version: 1.0
 * Author: Theme of the Crop
 * Author URI: http://themeofthecrop.com
 * License:     GNU General Public License v2.0 or later
 * License URI: http://www.gnu.org/licenses/gpl-2.0.html
 *
 * This program is free software; you can redistribute it and/or modify it under the terms of the GNU
 * General Public License as published by the Free Software Foundation; either version 2 of the License,
 * or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without
 * even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *
 * You should have received a copy of the GNU General Public License along with this program; if not, write
 * to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 */
defined( 'ABSPATH' ) || exit;

add_action( 'etfrtb_designer_setup', function($designer) {
  $designer->set('logo_width', 300);
  $designer->set('logo_height', 150);
});