Solution:
I’ve figured how to do that by selecting the last record and then get it as a collection to be able to update it.
$bcamps = Bcamp::raw()->findOne([],['sort' => ['_id' => -1],'projection' => ['_id' => 1]]);
$bcamps = Bcamp::where('_id', '=' , $bcamps->_id)->first();
Hope to save some other people time.