Smart collections are supposed to be sorted through the sort configuration set when editing the filters.
As for their display mode… smart collections will never hide their items – however they respect the display with regards if an individual smart collection is listed in-line of your main library or hidden (=only visible in the collections tab). Plex have commented that the Advanced tab of those smart collections has yet to obtain a clean-up (=remove the sort field, only offer display mode parameters that actually apply to smart collections).
There’s a very recent suggestion to support filtering by smart collections:
