Rest API C# Mapping Classes Best Approaches for complex objects

I have a complex json object which I am deserializing to dto class in API. While mapping this class to model class, I have tried two options:

1. IConverter interface and implementation for each class.
2. Static Mapper Classer

For eg: Json Object:

{
 "Response": 
          {
        "Detail": {
            "Subject": "GE",
            "Address": {
                "CountryCode": "US"
                      }
                  } 
       }
  }

For this Object, Response class would have property of type Detail class, which would have properties of type Subject ,Address etc.

Hence for 1st approach, I had to create separate class mapper for each class in source and destination. like:

public class DetailMapper<DetailDto, DetailModel>:IConvert<DetailDto, 
                          DetailModel>
{
   private IConvert<SubjectDto,SubjectModel> subconvert;
   private IConvert<AddressDto,AddressModel> addconvert;

    public DetailMapper(IConvert<SubjectDto,SubjectModel> 
                       sub,IConvert<AddressDto,AddressModel> add)
       {
            subconvert=sub;
            addconvert=add;
       } 

    public DetailModel Convert(DetailDto detailDto)
      {
       //logic
       }
   }

When JSON Object is more complex, this pattern is less readable with more converter implementations for each class injected.

2.For 2nd approach, I created single mapper class with static methods to convert dto classes to model like:

     public class Mapper()
    {
     public static ResponseModel Convert(ResponseDto res)
     {
      //logic
     }

      public static DetailModel Convert(DetailDto det)
      {
        //logic
       }
      }

2nd approach seems to be providing me more readability, but I am concerned if it is ok to use static methods for mapper class in Api.

I would like to know what are the best approaches and pattern for mapping 2 classes in c#.