test.cpp

#include <type_traits>

template <class ...Args, class = typename std::enable_if<sizeof...(Args) == 0>::type>
int maxSize() { return 0; }

template <class First, class ...Args>
int maxSize() {
    return sizeof(First) > maxSize<Args...>() ? sizeof(First) : maxSize<Args...>();
}

int main() {
    maxSize<>();
    maxSize<int, int>();
}