#include <type_traits>

template <typename... Types>
struct Pack { };

template <typename, typename>
struct Contains;

template <typename T, typename... Types>
struct Contains<T, Pack<Types...>>
{
    constexpr static bool value { (std::is_same_v<T, Types> || ...) };
};

template <typename, typename>
struct Is_Subset;

template <typename... Ts, typename T>
struct Is_Subset<Pack<Ts...>, T>
{
    constexpr static bool value { (Contains<Ts, T>::value && ...) };
};

template <typename T1, typename T2>
struct Are_Equal
{
    constexpr static bool value { Is_Subset<T1, T2>::value && Is_Subset<T2, T1>::value };
};

int main()
{
    using List = Pack<char, double, bool, int, bool, char>;

    static_assert( Contains<int, List>::value );
    static_assert( !Contains<unsigned, List>::value );

    static_assert( Is_Subset<Pack<int, char>, List>::value );
    static_assert( !Is_Subset<Pack<int, char, float>, List>::value );

    static_assert( Are_Equal<List, List>::value );
    static_assert( !Are_Equal<Pack<int, char>, List>::value );
}