CODE EXAMPLE FOR PHP

magento 2 add cc transportbuilder

<?xml version="1.0" encoding="UTF-8"?>
<!--
/**
 * MyCompany Email.
 */
-->
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <type name="MagentoFrameworkMailTemplateTransportBuilder">
        <plugin name="mycompany_email" type="MyCompanyEmailPluginCcPlugin"/>
    </type>
</config>