Upgrading C++ library features.

I'm currently running FreeBSD 15.1.  I found out that in c++20 you can now
say:

for(auto [i, j] : v | std::views:enumerate)

... which I would very much like to.  FreeBSD 15.1 has clang 19 as
standard, which supposedly support c++20 and more, but some searching leads
me to conclude that enumerate is a late addition to clang.

So I installed clang23 to see.  This still kicks out the error --- but I'm
expecting this is about include files.  Does clang23 come with new include
files --- or can I access them.  I suppose there is a similar question
about libc++ ... even though this specific problem doesn't involve the
library proper, AFAIK.

Help?