What caching is provided out of the box for Phoenix framework?

Doesn't seem to be mentioned in the page but if you're talking about request caching there's libraries like PlugHTTPCache or RequestCache.

Otherwise I usually use Nebulex (annotations are nice for Ecto queries) with ETS as it's faster than with Redis (if you don't care about losing the cache on deployment).

Out of the box in Elixir/Erlang, Phoenix is the web framework layer.