I want to use orderBy throw this array ?

You can use the collect() function in $users to transform your response in a Laravel collection. Then you can sort using the sortBy method.

$users = collect($json['documents'])
$sorted = $users->sortBy('created_at');

https://laravel.com/docs/7.x/collections#method-sortby

tnx so much.. but it will sort only 10 results (the limit value) .. can you help me to make it sort all results ?

First, remove your URL, because with the key, everyone can access your data.

Instead, insert a sample of the data, like

{
  "documents": [
    {
      "name": "......",
      "fields": {
        "created_at": {
          "timestampValue": "2020-08-27T14:41:40.508Z"
        }
      },
      "createTime": "2020-08-27T14:41:40.644088Z",
      "updateTime": "2020-09-08T10:48:50.207951Z"
    },
    {
      "name": "......",
      "fields": {
        "created_at": {
          "timestampValue": "2020-08-27T14:41:40.508Z"
        }
      },
      "createTime": "2020-08-27T14:41:40.644088Z",
      "updateTime": "2020-09-08T10:48:50.207951Z"
    },
    {
      "name": "......",
      "fields": {
        "created_at": {
          "timestampValue": "2020-08-27T14:41:40.508Z"
        }
      },
      "createTime": "2020-08-27T14:41:40.644088Z",
      "updateTime": "2020-09-08T10:48:50.207951Z"
    }
  ]
}

But what you want is to sort all tour results, so you have to check google api to check if exists an option to sort the result. If this option does not exists, put the results into a collection, then sort the collection (report to @pedroroccon message)