Object that stores multidimensional index that can be supplied in operator[]

Question

As C++23 supports multidimensional subscript operator(eg. a[1, 2, 3] and mdspan, is there native support for storing an multidimensional index as an object and used multiple times?

One example could be

// not storing as object {int a; double b;} due to layout considerations
// maybe we want contiguous accessing a/b individually to be fast but there are
// slow operations using both
std::array<std::array<std::array<int, L>, M>, N> a;
std::array<std::array<std::array<double,L>, M>, N> b;
// Index is conjured up
Index idx{3, 5, 2};
doSomething(a[idx], b[idx]);

Is there anything we would get from the mdspan library that achieve this? I feel this is actually something handy when doing operations above, but seems like we need to implement ourselves.