What design pattern I should use in my context?

I work with Symfony project. I'm a newbie with design pattern and I would like to apply it. My context is : I would like have a function receive an input json -> decode into an array -> get some necessary data in that array -> store in a column of a table with json type. My expected with my function when apply design pattern is : it could receive different structure json, but finally, it will return same structure json. Example:

• Input json 1:

{
   "contactdata": {
        "mobilephone": "",
        "email": ""
    },
    "userdata": {
        "birthday": {
            "status": "",
            "value": "1/1/2021"
        },
        "firstname": {
            "status": "",
            "value": "My first name 1",
        },
        "lastname": {
            "status": "",
            "value": "My last name 1",
        }
    } 
}

Expected return json:

{
    "first_name" : "My first name 1",
    "last_name": "My last name 1",
    "birthday": "1/1/2021"
}

• Input json 2:

{
    "STATUS": true,
    "PERSONALDETAILS": {
        "APPLICANTFIRSTNAME": "My first name 2",
        "APPLICANTLASTNAME": "My last name 2",
    }
}

Expected return json:

{
    "first_name" : "My first name 2",
    "last_name": "My last name 2",
    "birthday": ""
}

I see many design pattern type and I'm learning about Visitor. I don't know if it could apply for my context or another design pattern will be better?