qiniu-php-sdk/examples/rs_change_type.php

<?php
require_once __DIR__ . '/../autoload.php';

use \Qiniu\Auth;

$accessKey = getenv('QINIU_ACCESS_KEY');
$secretKey = getenv('QINIU_SECRET_KEY');
$bucket = getenv('QINIU_TEST_BUCKET');

$key = "qiniu.mp4";
$auth = new Auth($accessKey, $secretKey);
$config = new \Qiniu\Config();
$bucketManager = new \Qiniu\Storage\BucketManager($auth, $config);

$fileType = 1;//0 表示普通存储，1表示低频存储

$err = $bucketManager->changeType($bucket, $key, $fileType);
if ($err) {
    print_r($err);
}