Expanding integer-sequence template-param in compile time

I am a bit uncertain about how to achieve variadic-expansion in compile time. Consider the below use-case where I'd like to figure out the index of the max-element in the sequence:

template<A>
struct doSomething {
  static constexpr int getIndexOfMaxValue() {
    // recursive variadic expansion
  }

  static constexpr int value = getIndexOfMaxValue();
}

int main() {
   std::cout << doSomething<std::integer_sequence<int, 1, 2, 3, 4, 3>::value <<std::endl;
}

Can someone kindly help me explain this?