API Design of login and refresh JWT token endpoint questions

{
    "userName": "Barocco",
    "accessToken": {
        "tokenString": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJqdGkiOiJiNTAyZTYzZC1lYTYwLTQ4MTktYTc0Ny00ZGI4YmNiY2U3YzkiLCJlbWFpbCI6ImxsQHd3IiwidW5pcXVlX25hbWUiOiJCYXJvY2NvIiwicm9sZSI6IkFkbWluIiwibmJmIjoxNjYzOTIzOTAxLCJleHAiOjE2NjM5MjM5MDYsImlhdCI6MTY2MzkyMzkwMSwiaXNzIjoiaHR0cHM6Ly9sb2NhbGhvc3Q6NTAwMS8iLCJhdWQiOiJodHRwczovL2xvY2FsaG9zdDo1MDAxLyJ9.I64OFaR9xnP2VmROBnv2RBNmGdAmbBVUn9kvocUN0Sc",
        "expireAt": "2022-09-29T14:16:35.0050936Z"
    },
    "refreshToken": {
        "tokenString": "JaXYg8r6NCJPD4g3JoQuyKIK4mWV/Be+J+B+QPshPfk=",
        "expireAt": "2022-10-22T14:16:35.0050936Z"
    },
    "role": "Admin"
}