Multilines message into WhatsApp API Using Textarea, POST and json playload with PHP

i am using WhatsAPP API of One of Facebook Partner.

I have a form with text area , Message content of textarea is POSTed to sendWhatsApp.php
and inside of sendWhatsApp.php i pasted following API code.

<?php
if(isset($_POST["textareacontent"])){
$message = $_POST["textareacontent"];

$url = "https://my-api-vender.com/api/send";

$curl = curl_init($url);
curl_setopt($curl, CURLOPT_URL, $url);
curl_setopt($curl, CURLOPT_POST, true);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);

$headers = array(
   "Content-Type: application/jsonrn",
);
curl_setopt($curl, CURLOPT_HTTPHEADER, $headers);

$data = '
{
 "app": {
"id": "79912580897",
"time": "1651738553",
"data": {
  "recipient": {
    "id": "923336458112"
  },
  "message": [
    {
      "time": "1651738553",
      "type": "text",
      "value": "'.$message.'"
    }
  ]
}
  }
}
';

curl_setopt($curl, CURLOPT_POSTFIELDS, $data);
curl_setopt($curl, CURLOPT_SSL_VERIFYHOST, false);
curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, false);

$resp = curl_exec($curl);
curl_close($curl);
}

This code is workin fine with single line message.
but web i enter special charachters , Unicode carachters or ani emoji its shwoing erro.
So please help me how can i send multiline message also how can i use special charaehters, unicode and emojis.