how to extend the metadata in TYPO3 10.4.13 - typo3

Question

I am trying to add a description field under the page properties/metadata which was still present in the TYPO3 8.7.32 version.
I have also already tried in the setup with the following code:
page.meta.description.field = description
#page.meta.description.ifEmpty =
currently it looks like this
and should look like this

Answer 1

If your goal is to add a SEO description field, this field is already available in the SEO tab.
Nevertheless, if you want to add a new field in metadata, you have to :
Add the new field in : your_ext/ext_tables.sql
CREATE TABLE pages (
new_field varchar(255) DEFAULT '' NOT NULL
);
Override the TCA : create or update the file your_ext/Configuration/TCA/Overrides/pages.php
<?php
defined('TYPO3_MODE') or die();
use TYPO3\CMS\Core\Utility\ExtensionManagementUtility;
call_user_func(static function () {
// Define new TCA field
$additionalFields = [
'new_field' => [
'exclude' => false,
'l10n_mode' => 'prefixLangTitle',
'label' => 'LLL:EXT:your_ext/Resources/Private/Language/locallang_db.xlf:pages.your_ext',
'description' => 'LLL:EXT:your_ext/Resources/Private/Language/locallang_db.xlf:pages.your_ext.description',
'config' => [
'type' => 'input',
'size' => 60,
'max' => 255
]
]
];
// Add the new TCA columns
ExtensionManagementUtility::addTCAcolumns('pages', $additionalFields);
// Add the field to the palette
ExtensionManagementUtility::addFieldsToPalette('pages', 'metatags', 'new_field', 'after:keywords');
});
Then you have to update the DB with BE module Maintenance > Analyze Database Structure.
Flush all cache - because TCA are in cache.
And your new field will now be available.