example.php

<?php

// $pageIdList is an array of integers (make sure it is!)

…

        /** @var QueryBuilder $queryBuilder */
        $queryBuilder = GeneralUtility::makeInstance(ConnectionPool::class)
            ->getQueryBuilderForTable('pages');

        $queryBuilder->select(uid)
                ->orderBy('FIELD(uid,' . implode(',', $pageIdList) . ')', null, false)

…

ext_localconf.php

<?php

defined('TYPO3_MODE') or die ('Access denied.');

(static function () {
    $GLOBALS['TYPO3_CONF_VARS']['SYS']['Objects'][\TYPO3\CMS\Core\Database\Query\QueryBuilder::class] = [
        'className' => \Vendor\Extension\Database\Query\QueryBuilder::class
    ];
})();

QueryBuilder.php

<?php
declare(strict_types=1);

namespace Vendor\Extension\Database\Query;

class QueryBuilder extends \TYPO3\CMS\Core\Database\Query\QueryBuilder
{
    /**
     * Specifies an ordering for the query results.
     * Replaces any previously specified orderings, if any.
     *
     * @param string $fieldName The fieldName to order by.
     * @param string $order The ordering direction. No automatic quoting/escaping.
     * @param bool $quote Flag if to quote the given field name.
     * @return QueryBuilder This QueryBuilder instance.
     */
    public function orderBy(string $fieldName, string $order = null, bool $quote = true): \TYPO3\CMS\Core\Database\Query\QueryBuilder
    {
        $this->concreteQueryBuilder->orderBy($quote ? $this->connection->quoteIdentifier($fieldName) : $fieldName, $order);

        return $this;
    }
}