How to display thumbnails in it's original size with PHP

Hi! 

I am trying to display my Dropbox images on the browser using /get_thumbnail which works just fine.

However, the image on the browser it's too small. It's not the original size.

This is the png image on my Dropbox account:

And this is the same image I got from the API:

As you can see, it's impossible to see the image.

So anyone knows how do I get the image in it's original size? I am using a PHP code as follow to browser the images:

<?php 

require_once 'Functions/functions.php';

header("Content-Type: image/jpeg");

$token = getToken($_SESSION['uid']);

if (isset($token[0])) {

    //$data  = file_get_contents('json/getThumbnail.json');

    $ch = curl_init();
    
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "POST");
    curl_setopt($ch, CURLOPT_HTTPHEADER, array('Authorization: Bearer ' . $token[0]->itoken, 'Dropbox-API-Arg: {"path": "/test-1/Capture-desktop.PNG", "format": "png", "mode": "strict"}'));
    curl_setopt($ch, CURLOPT_URL, "https://content.dropboxapi.com/2/files/get_thumbnail");
    
    $response = curl_exec($ch);

    echo $response;

}else{
    header('Location: http://localhost/optiSurface-dropbox/curl-auth1.php');
    exit();
}

 ?>

I appreciate if anyone can help me out with this issue.

Cheers!!