php - how to Data manipulation in laravel resource

one text

i want to manipulate my data in resource collection this is my Resource Collection :

requestState is my Model Relationship

class RequestResource extends JsonResource
{

    public function toArray($request)
    {
        return [
            'requestId'=>$this->id,
            'user'=>$this->user->profile->name." ".$this->user->profile->family,
            'submitDate'=>$this->created_at,
            'requestState'=>$this->requestState()->latest('decided_at')->first(),
            'field'=>'kardani computer',

        ];
    }


}

this is json that return from the resource

{
    "data": {
        "requestId": 63,
        "user": "???�?�?�?� ?�?�?�?�?�??",
        "submitDate": "2021-05-17T13:00:48.000000Z",
        "requestState": {
            "id": 27,
            "request_id": 63,
            "confirm": null,
            "description": null,
            "decided_at": "2021-06-23 17:30:48",
            "created_at": "2021-05-17T13:00:48.000000Z",
            "updated_at": "2021-05-17T13:00:48.000000Z",
            "department_id": 3
        },
        "field": "kardani computer"
    }
}

i want to manipulate "requestState" relation model Data and show whatever i want or change data and return in RequestResource Do I need to define a resource for RequestState ? And call it in RequestResource?

                'requestState'=>$this->requestState()->latest('decided_at')->first(),