How can last row if last row is 003

how do I add +1 data if the last data type varchar data is in format 001, 002, 003 , i try that but results is 1

 $nis = Profile::all()->last();
        $nisnow = $nis->nis += 1;
        dd($nisnow);

Edited : my expect results if last data 003 + 1=004

via Chebli Mohamed