ext_tables.php

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

call_user_func(function () {

    /**
     * FE Plugin
     */
    \TYPO3\CMS\Extbase\Utility\ExtensionUtility::registerPlugin('femanager', 'Pi1', 'FE_Manager');

    /**
     * Include Backend Module
     */
    if (!\In2code\Femanager\Utility\ConfigurationUtility::isDisableModuleActive() &&
        !(TYPO3_REQUESTTYPE & TYPO3_REQUESTTYPE_INSTALL)) {
        \TYPO3\CMS\Extbase\Utility\ExtensionUtility::registerModule(
            'In2code.femanager',
            'web',
            'm1',
            '',
            [
                'UserBackend' => 'list,confirmation,userLogout,confirmUser,refuseUser,listOpenUserConfirmations,resendUserConfirmationRequest,unsubscribe'
            ],
            [
                'access' => 'user,group',
                'icon' => 'EXT:femanager/ext_icon.svg',
                'labels' => 'LLL:EXT:femanager/Resources/Private/Language/locallang_mod.xlf',
            ]
        );
    }

    /**
     * Static TypoScript
     */
    \TYPO3\CMS\Core\Utility\ExtensionManagementUtility::addStaticFile(
        'femanager',
        'Configuration/TypoScript/Main',
        'Main Settings'
    );
    \TYPO3\CMS\Core\Utility\ExtensionManagementUtility::addStaticFile(
        'femanager',
        'Configuration/TypoScript/Layout',
        'Add Layout CSS'
    );

    /**
     * Add user TSConfig
     */
    \TYPO3\CMS\Core\Utility\ExtensionManagementUtility::addUserTSConfig(
        '<INCLUDE_TYPOSCRIPT: source="FILE:EXT:femanager/Configuration/UserTsConfig/BackendModule.typoscript">'
    );

    /**
     * Flexform
     */
    $pluginSignature = str_replace('_', '', 'femanager') . '_pi1';
    $GLOBALS['TCA']['tt_content']['types']['list']['subtypes_addlist'][$pluginSignature] = 'pi_flexform';
    \TYPO3\CMS\Core\Utility\ExtensionManagementUtility::addPiFlexFormValue(
        $pluginSignature,
        'FILE:EXT:femanager/Configuration/FlexForms/FlexFormPi1.xml'
    );

    /**
     * Disable non needed fields in tt_content
     */
    $GLOBALS['TCA']['tt_content']['types']['list']['subtypes_excludelist']['femanager_pi1'] = 'select_key';

});