Official versions of this content were provided for free to players who already owned the Civilization VI Anthology or all previous DLCs on Steam and Epic Games Store.
I can dive deeper into the for these specific leaders or look up the patch notes from that specific March 2023 update.
Minor tweaks to the Korean and Byzantine civ abilities to accommodate the new leader styles. Release Technicalities
Known as the "Mad King," he focuses on Wonders and Culture. His "Swan King" ability allows Wonders to provide +2 Culture for every adjacent District, even if the Wonder isn't finished. Key Game Updates
Focuses on Holy Sites and Culture. Her "Restorer of Icons" ability allows Holy Sites to provide Culture equal to their adjacency bonus.
Along with these leaders, the update associated with this release included several balance changes:
Civilization VI: Leader Pass – Great Builders Pack Release Date: March 29, 2023 Release Type: P2P (Peer-to-Peer) scene distribution