As always, Final Fantasy XIV's new 4.2 patch is accompanied by a massive notes dump, and you can read the preliminary notes now (Square Enix refrains from publishing exact numbers, until right before the patch actually drops, especially for item values, to prevent economy gaming).
As expected it'll come with a new four-party raid that's based on bosses from Final Fantasy VI, a new trial, two more dungeons, more story content, and a ton more. Many things are quality of life focused, like more inventory space (by way of a Chocobo pack), additional housing items, instant teleportation to the houses of friends, a baked-in recording feature (currently just for the new trial, with further testing to occur), more "perform" (read: in-game instrument) actions, class balancing (Warrior, or "WAR" was changed the most), the shaking up of various roulette (ways to do old content for currency rewards), and a lot more.
It took me roughly 30 minutes to really take it all in, so get to reading this weekend before 4.2 drops on Tuesday!
Patch 4.2 Notes (Preliminary) [Final Fantasy XIV]
via destructoid https://www.destructoid.com/final-fantasy-xiv-s-4-2-massive-patch-notes-detail-changes-classic-boss-fights-484593.phtml