You can try like this :
$userData = array("username" => "admin", "password" => "admin123");
$ch = curl_init("http://magento213/index.php/rest/V1/integration/admin/token");
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "POST");
curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($userData));
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, array("Content-Type: application/json", "Content-Length: " . strlen(json_encode($userData))));
$token = curl_exec($ch);
$order_number = '1';
$ch = curl_init("http://magento213/index.php/rest/V1/orders/" . $order_number);
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "GET");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, array("Content-Type: application/json", "Authorization: Bearer " . json_decode($token)));
$result = curl_exec($ch);
$result = json_decode($result, 1);
echo '<pre>';print_r($result);
For More Info Here Is The Reference Link :
https://magento.stackexchange.com/questions/154198/magento-2-how-to-get-order-information-using-rest...
