In modern C++, std::mdspan is a flexible solution for multidimensional arrays with sizes only known at runtime, providing a view over contiguous memory without multiple allocations. However, it can be verbose, and while it isn’t as concise as std::vector, it minimizes overhead. Alternatively, libraries like Eigen or Boost.MultiArray offer robust multidimensional array handling with runtime sizing and may be more straightforward if additional dependencies are acceptable. Standard support for dynamic multidimensional arrays has been limited by complexity and performance considerations, making these alternatives the best current options.