Is there a way to easily handle functions returning std::pairs?

With structured binding from C++17, you may directly do

auto [lhsMinIt, lhsMaxIt] = std::minmax_element(lhs.begin(), lhs.end());

To avoid polluting your scope, you could enclose the assignment in a smaller scope:

int lhsMin, lhsMax;

{
    auto it = std::minmax_element(lhs.begin(), lhs.end());
    lhsMin = *it.first;
    lhsMax = *it.second;
}

alternatively, you can use a lambda

int lhsMin, lhsMax;

std::tie(lhsMin, lhsMax) = [&]{
    auto it = std::minmax_element(lhs.begin(), lhs.end());
    return std::make_tuple(*it.first, *it.second);
}();

This looks like enough of a common case to prompt a helper function:

template <class T, std::size_t...Idx>
auto deref_impl(T &&tuple, std::index_sequence<Idx...>) {
    return std::tuple<decltype(*std::get<Idx>(std::forward<T>(tuple)))...>(*std::get<Idx>(std::forward<T>(tuple))...);
}

template <class T>
auto deref(T &&tuple)
    -> decltype(deref_impl(std::forward<T>(tuple), std::make_index_sequence<std::tuple_size<std::remove_reference_t<T>>::value>{})) {
    return deref_impl(std::forward<T>(tuple), std::make_index_sequence<std::tuple_size<std::remove_reference_t<T>>::value>{});
}

// ...

int lhsMin;
int lhsMax;
std::tie(lhsMin,lhsMax) = deref(std::minmax_element(lhs.begin(), lhs.end()));

index_sequence is C++14, but a full implementation can be made in C++11.

Note: I'd keep the repeated decltype in deref's return type even in C++14, so that SFINAE can apply.

See it live on Coliru