Laravel - How to save API rest endpoint data into my database

I am using Laravel 5.8 in my server. I have this external endpoint:

https://api.abclm.net/customerss/allcustomers

It is a GET Request and in JSON the format as shown below.

[
  {
    "ClientID": "C001",
    "ClientName": "ABU PLC",
    "Address": "ADDRESS LINE 1",
    "City": "Lagos"
  },
    "ClientID": "C002",
    "ClientName": "ADE PLC",
    "Address": "ADDRESS LINE 1",
    "City": "Lagos"
  },
    "ClientID": "C003",
    "ClientName": "JACOB PLC",
    "Address": "ADDRESS LINE 1",
    "City": "Lagos"
  }
]

Then, in my server I have this table:

 CREATE TABLE `customers` (
`id` int NOT NULL,
`client_id` varchar(255) UNIQUE NOT NULL,
`client_name` varchar(255) UNIQUE NOT NULL,
`address` varchar(255) NOT NULL,
`city` varchar(255) NOT NULL

) ENGINE=MyISAM DEFAULT CHARSET=latin1;

The model class is Customer.

1. client_id and client_name are unique and should be reference points.

2. I want to save all the data in the endpoint at the same time in my Customer model class.

3. It should update where client_id and client_name already exists but insert where not

4. ClientID into client_id, ClientName into client_name, Address into address

I have something like this, but don't know how to continue:

public function apiclient(Request $request)
{
        $array_content=[];

     $ch = curl_init();
        curl_setopt($ch, CURLOPT_URL, "https://api.abclm.net/customerss/allcustomers");
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false); //Important
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
        curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "GET");
        $result = curl_exec($ch);

        if (curl_errno($ch)) {
            echo 'Error:' . curl_error($ch);
        }
          curl_close ($ch);
    $i=0;
    foreach(...)
    {
    $newobj = new Clients();

    ....
    array_push($array_content,$newobj);

    $i++;
    }
    return $array_content;
}

I have something like this but don't know how to go about it. Kindly assist.

Instead of using manual curl, I find this Guzzle wrapper easier. http://docs.guzzlephp.org/en/stable/

$client = new GuzzleHttp\Client();
$res = $client->request('GET', 'https://api.abclm.net/customerss/allcustomers');
return $res->getBody();