ujiancbt The nginx conf on host server should not be edited directly in any way.
It serves only for handling SSL and proxy everything identically to the user container.
You as an Admin, or Users directly, should edit only the configuration files inside their container. If user has apache - all directives supported on that version can be used.
Same if user is using nginx as webserver, every nginx directive can be used. Examples on cache with wp purge cache: https://www.google.com/search?q=nginx+fascgi+cache+with+WP+cache+purge