Get rows where created date is older than 14 days

You can use Carbon::now()->subDays(14)

    $passed = Deployment::where('created_at', '>=', Carbon::now()->subDays(14)->toDateTimeString());

You can read more about Carbon its feature here Carbon Documentation

You can use the subDays() method:

$passed = Deployment::where('created_at', '<=', Carbon::now()->subDays(14)->toDateTimeString());