ext_localconf.php

<?php
if (!defined('TYPO3_MODE')) {
    die('Access denied.');
}

// Register for hook to show preview of tt_content element of CType="wstextmediabootstrap" in page module
$GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['cms/layout/class.tx_cms_layout.php']['tt_content_drawItem']['wstextmediabootstrap']
    = Websight\WsTextmediaBootstrap\Preview\WsTextmediaPreviewRenderer::class;

if (TYPO3_MODE === 'BE') {
    call_user_func(
        function ($extKey) {
            // Get the extension configuration
            $extConf = unserialize($GLOBALS['TYPO3_CONF_VARS']['EXT']['extConf'][$extKey]);

            if (!isset($extConf['loadContentElementWizardTsConfig']) || (int)$extConf['loadContentElementWizardTsConfig'] === 1) {
                // Include new content elements to modWizards
                \TYPO3\CMS\Core\Utility\ExtensionManagementUtility::addPageTSConfig('<INCLUDE_TYPOSCRIPT: source="FILE:EXT:ws_textmedia_bootstrap/Configuration/PageTSconfig/NewContentElementWizard.typoscript">');
            }
        },
        $_EXTKEY
    );
}