使用Croppie在PHP中调整图像大小

I am trying to resize an image which is taken from a cropping tool used on my form. The code below is being used with the library Croppie.

if($_POST['imagebase64'] != '') {
    $data = $_POST['imagebase64'];

    list($type, $data) = explode(';', $data);
    list(, $data)      = explode(',', $data);
    $data = base64_decode($data);

    file_put_contents(APPPATH.'../assets/image64.png', $data);
}

I would like to know how to resize the image before pushing it to the server. Preferably, I would like to use stock php, something like imagecopyresampled but I'm not sure how to go about it.

Any help would be much appreciated.