You can use dot notation to access nested relationships. To quote the Laravel Documentation.
To eager load nested relationships, you may use "dot" syntax. For example, let's eager load all of the book's authors and all of the author's personal contacts in one Eloquent statement:
$books = App\Book::with('author.contacts')->get();
In your case, this would look something like:
$citydetails = City_table::with('states.countries')->find($id);