newsupernova/vendor/magento/module-webapi/etc/adminhtml/system.xml

<?xml version="1.0"?>
<!--
/**
 * Representation of Webapi module in System Configuration (Magento admin panel).
 *
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */
-->
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Config:etc/system_file.xsd">
    <system>
        <section id="webapi" translate="label" type="text" sortOrder="102" showInDefault="1" showInWebsite="1" showInStore="1">
            <label>Magento Web API</label>
            <tab>service</tab>
            <resource>Magento_Webapi::config_webapi</resource>
            <group id="soap" translate="label" type="text" sortOrder="1" showInDefault="1" showInWebsite="1" showInStore="1">
                <label>SOAP Settings</label>
                <field id="charset" translate="label comment" type="text" sortOrder="10" showInDefault="1" showInWebsite="1" showInStore="1">
                    <label>Default Response Charset</label>
                    <comment>If empty, UTF-8 will be used.</comment>
                </field>
            </group>
        </section>
    </system>
</config>