This quest takes place entirely during cutscenes, which begin after the end of “Fall of an Empire, Rise of Another” . Why this needed to be its own quest is anybody’s guess, as there’s not a single moment during its entirety where you control anything. Still, it’s a fine time to talk about the few post-game changes.
After this quest ends, you’ll be back in control of Bayek, who is at the fast travel point in the northeastern corner of the temple complex in Memphis. Any unresolved side quests can be tackled now, as can points of interest and, of course, various other events like hippodrome races, arena fights and “Trial of the Gods” events. In fact, the only appreciable thing that has changed (aside from the obvious absence of main quests) is the formation of an Assassin’s Bureau - the Bureau of The Hidden Ones - in the northeastern edge of Memphis.
Fast travel there, if you wish, and you’ll find a variety of scrolls lying about, giving you details on various potential allies and examples of post-game content (Phylakes, Stone Circles, war elephants) that may be left to do, most of which are covered in the Unfinished Business section of the guide. Also interesting is the Hidden Ones provisioner you can talk to, who will sell a random variety of legendary gear, and unlimited Tablets of Knowledge… which essentially allow you to trade 1,000 Drachmas for a similar amount of experience. You know, in case you have money burning a hole in your purse and nothing better to spend it on but empowering Bayek.
Clear up any remanding side quests or points of interest, go hunt trophies/achievements, everything should be included in its appropriate place in the guide above, With that, you’re done with Assassin’s Creed Origins!