Google is your friend, so is Wikipedia.
From the GCC website, we can see that there is experimental/support for C++17 standard, through the -std=c++17 flag.
From this awesome wiki article, there is a cross reference list for functionality and features. It indicates that std::any is supported in version GCC >= 7, but only on Clang (which may be what you are using on accident) version Clang >= 4.
Post the command you are running for some extra help, and make sure you have the corresponding header, included in your file(s).
solved c++ is there a flag for c++17 osx 10.13.6