سلام.

کوئری رو به شکل زیر بنویسید. (نام جدولو داخل بک کوت بیارید):

$sql = "INSERT INTO `php_expert` (`title`,`content`,`status`) VALUES (?,?,?)";

بعد از foreach دستور exit رو هم پاک کنید تا commit انجام بشه.

# PDO CONNECTION
list($host, $dbname, $user, $pass) = ['localhost', 'wpmain', 'root', ''];
try {
    $pdo = new PDO("mysql:host={$host};dbname={$dbname};charset=utf8mb4", $user, $pass, array(PDO::ATTR_PERSISTENT => true));
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
} catch (PDOException $e) {
    echo "Error message: " . $e->getMessage();
}
# Insert Data in DB
$posts = [
    ['post 1', 'content post 1', 'publish'],
    ['post 2', 'content post 2', 'trash'],
    ['post 3', 'content post 3', 'draft'],
];
try {
    $pdo->beginTransaction();
    $sql = "INSERT INTO `php_expert` (`title`,`content`,`status`) VALUES (?,?,?);";
    $stmt = $pdo->prepare($sql);
    foreach ($posts as $post) {
        $stmt->execute($post);
    }
    exit();
    $pdo->commit();
} catch (PDOException $e) {
    echo "Error: " . $e->getMessage();
}