Hur ställer jag in en kollation med mysqli?

mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$mysqli=mysqli_connect('mysql01','username','password', 'my_database');
$mysqli->set_charset('utf8mb4');
// setting collation is optional and not needed 99% of time
// only if you need a specific one, like in this case
$mysqli->query("SET collation_connection = utf8mb4_czech_ci");