Could not send nested multi dimensional json object POST request in PHP

Question

I have a nested multi dimensional json object and I want to make a post request with this json but I did not find a direct way to send post request with this json because I did not find a way to declare a json object in php and even i cant convert this json_object to array because of the posted data corrupted

json_object={
    "messages": {
        "authentication": {
            "productToken": "your product token"
        },
        "msg": [{
            "body": {
                "type": "auto",
                "content": "Fallback Text for SMS"
            },
            "to": [{
                "number": "00316012345678"
            }],
            "from": "00316098765432",
            "allowedChannels": ["WhatsApp"],
            "richContent": {
                "conversation": [{
                    "text": "A text message with *bold* formatting in a speech bubble."
                }, {
                    "text": "Another speech bubble"
                }, {
                    "media": {
                        "mediaName": "and an image",
                        "mediaUri": "https://www.cm.com/cdn/web/nl-nl/blog/conversational-commerce.jpg",
                        "mimeType": "image/jpeg"
                    }
                }]
            }
        }]
    }
}

i want to make a post request with this json_object but i cant declare a json object in php so i should Convert My json_object to Array but i could not convert this json_object to array without corrupting request data

this is my code

$data = http_build_query($json_object);
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, $data);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$resp = curl_exec($ch);
if($e = curl_error($ch)) {
    echo $e;
}
else {
    $decoded=json_decode($resp);
    foreach($decoded as $key => $val) {
        echo $key  . ':'. $val. '<br>';
    }
}
curl_close($ch);

Can anyone help me sending this post request please ?