How to join results as an array of objects and filter, sort and paginate them in Laravel?

I have been working a project where activities can be graded in different ways using competences. Among many, I have two tables schemas that I am working on.

Table: Activities

1. id
2. name
3. isNewest //currently always 1

Table : activity_competences //link table between activities, framework_competences and sub_competences

1. id
2. activity_id (foreign_key)
3. framework_competence_id
4. master_competence_id

Table : framework_competences

1. id
2. name

Table : master_competences

1. id
2. name

I want to fetch all the activities and its corresponding competences using SQL join.
I also want the user to be able to filter and sort these results so they can only see the activities with the competence they need.

This is what I currently have.

        $paginateOffset = isset($request->paginateOffset) ? $request->paginateOffset : 0;
        $currentSort = isset($request->currentSort) ? $request->currentSort : 'id';
        $currentSortDir = isset($request->currentSortDir) ? $request->currentSortDir : 'desc';


        $activities = Activity::where('isNewest', 1)
        ->leftJoin('activity_competences', 'activities.id', '=', 'activity_competences.activity_id')
        ->leftJoin('framework_competences', 'activity_competences.framework_competence_id', '=', 'framework_competences.id')
        ->leftJoin('master_competences', 'activity_competences.master_competence_id', '=', 'master_competences.id')
        ->where(function($query) use ($request){//filter using keyword that user enters.
            $query->where('activities.name', 'LIKE','%'.$request->keyword.'%')
            ->orwhere('framework_competences.name', 'LIKE','%'.$request->keyword.'%')
            ->orwhere('master_competences.name', 'LIKE','%'.$request->keyword.'%');
        })->orderBy($currentSort, $currentSortDir)->offset($paginateOffset)->limit($paginateAmmount)
        ->get(array('activities.*', 'framework_competences.name as framework_competences', 'master_competences.name as master_competences'));

The response I get is:

[
    {
        "id": 1,
        "name": "activity1",
        "framework_competences": 'name1',
        "master_competences": 'name3',
        "isNewest": 1
    },
    {
        "id": 2,
        "name": "activity2",
        "framework_competences": 'name2',
        "master_competences": 'name4',
        "isNewest": 1
    }
]

but what I would like is:

[
    {
        "id": 1,
        "name": "manjil",
        "framework_competences": [name1, name2],
        "master_competences": [name3, name4]

    }
]