I used to live and breath C++ early 2000s, but haven't touched it since. I can't make sense of modern C++.
A lot of it is about making metaprogramming a lot easier to write and to read.
No more enable_if kludges since if constexpr (and concepts for specific stuff); and using concepts allows to better communicate intent (e.g.: template<typename I> can become template<std::integral I> if you want the template to be used only with integer types, and so on)
I wrote a lot of plain C and a lot of C++ (cumulatively probably close to MLoC) and I can't remember any C code that would compile in such a short time unless it was a library code or some trivial example.