Compared to what? Modern C++ is by far the most expressive systems language. That is its primary selling point. It isn’t pretty but it is uniquely powerful. One of the reasons C++ isn’t disappearing any time soon is that it elegantly and efficiently handles some software design problems that Rust struggles with. Rust and C++ are optimized for different types of software.
As is implied, the type of software someone is writing has a large impact on whether or not they need the expressiveness of C++.
If you want to iterate over a range of integers, you need to manually explain to the computer how to do it. In 2023. Also, you need to Write Everything Twice because of the ancient header system.
Modules are not supported by most compilers (in g++ you have to enable them as an experimental feature with -fmodules-ts, and if you want to import the standard library as modules, you need to pre-compile them into your project directory with some arcane commands).
Modules: GCC and clang will eventually get there, I am already enjoying them on VC++
#define RANGE(type, name, last) type name = 0, last__ = (last); name != last__; name++
for (RANGE(i32, i, foo->count))
...
Once you you've worked enough with proper enums and matches, that's the first thing you'll be lacking in C++ (and no, std::variant is a horrible mess without proper syntax support and doesn't even get close).
I feel that you are the very first person ever making such a statement. Can you provide what's your single best example showing C++'s inexpressiveness and "high impedance with cognition"?
C++ has lots of problems, lack of expressiveness isn't one of them.