This site seem only to reference is only up to C++11. Newer standards have introduce newer C++ standard Libraries

If you want an up-to-date C/C++ reference: https://en.cppreference.com/w/cpp

If you want a C++ tutorial that covers many of the newer features of C++: https://www.learncpp.com/

CPlusPlus is not likely to be updated.

This site covers C++14, but is unlikely to be updated now to cover C++17/20. The best reference to the newer standard is as per Furry Guy's post.

There's also https://en.cppreference.com/w/cpp/compiler_support which details the changes between the various standards and compiler support - which now details changes to C++23!