Current Events > Stellaris 2.3 and Ancient Relics patch notes

(+) Yeah! (+)

https://forum.paradoxplaza.com/forum/index.php?threads/stellaris-dev-diary-150-2-3-wolfe-patch-notes.1183870/
Major note: they've completely reworked sectors, allowing you to designate a "sector capital" that hoovers up surrounding worlds to make a sector, rather than it just...happening.
Other things...
The expansion features archaeological projects, two new pre-cursors, minor artifacts that can expended for a one-time boost(what those boosts are rely on your ethics), and relic worlds, which are stuffed with artifacts and relics.

The patch introduces relics, which can be acquired via a number of ways. For example, the Contingency Core, Prethoryn Queen, the Great Khan's throne, and the Galatron are now all relics which may be activated for special benefits(IIRC, the Queen will generate a small Prethoryn fleet for you). Lastly, Habitats and Ringworlds got a buff.