change the time format of laravel datatables

There are a lot of way to do that, you can do it from your controller as :

return Datatables::of($query)
  ->addColumn('created_at', function ($row){
       return $row->created_at->format('d-M-Y');
})

Alternative : Laravel 7 uses a new date serialization format when using the toArray or toJson method on Eloquent models. Previously, dates would be serialized to a format like the following :

2020-12-02 20:01:00

Dates serialized using the ISO-8601 format will appear like :

2020-12-02T20:01:00.283041Z

If you would like to keep using the previous behavior you can override the serializeDate() method on your model :

use DateTimeInterface;

protected function serializeDate(DateTimeInterface $date)
{
    return $date->format('Y-m-d H:i:s');
}

See the official upgrade doc here