Best way to create a generic handler for all return types in c#

I have a bunch of classes and I want to group them functionally leveraging generics.

Below are my interface and classes:

public interface IMessagePoster<TReceiptType> 
{
    TReceiptType postMessage(Message message);
}

public class FacebookPoster : IMessagePoster<FacebookReturnType> {}
public class TwitterPoster : IMessagePoster<TwitterReturnType> {}
public class InstagramPoster : IMessagePoster<InstagramReturnType> {}

I now am interested in creating a generic handler class that is able to return the appropriate return type based on the generic type provided.

public class SocialPostHandler<TSocialType, TPostReturnType>
 where TSocialType: IMessagePoster<TPostReturnType>, new()
{
    public TPostReturnType postMessage(Message message) => new SocialType().postMessage(message);
}

When I call it I have to pass in the class type as well as return type.

new SocialPostHandler<FacebookPoster, FacebookReturnType>(message);

Is there a better way to achieve this generic handler SocialPostHandler? Anything that would help me infer the type somehow would also help. Thanks!