Laravel how to modify the returned result from eloquent to convert json string to json object

Question

Description and welcomeEmailContents are type text in db ,and both store same type data . Description return json obj while issue is welcomeEmailContents return string.

$course_desc_blocks = ($courseData['description'] != null) ? json_encode($courseData['description']) : null;
$course_welcome_blocks = ($courseData['welcomeEmailContents'] != null) ? json_encode($courseData['welcomeEmailContents']) : null;
    
//Laravel Query:-
 $courseData = Course::select('id', 'title', 'description','welcomeEmailContents', 'price', 'site_id', 'status', 'expiry_days')->orderBy('id', 'asc'));
return response()->json( $courseData );
//===================================== 
//output
{
  "data": {
    "id": 100,
    "title": "Python",
    "description": [
      {
        "type": "paragraph",
        "data": {
          "text": "jsonTesting"
        }
      }
    ],
    "welcomeEmailContents": "[{\"type\":\"paragraph\",\"data\":{\"text\":\"Testingjson\"}}]",
    "price": 0
  }
  
}