In the two-part "Discovery" episode "Terra Firma" (December 10 and 17, 2020), the evil Empress Georgiou (Michelle Yeoh) from the Mirror Universe passed through the sentient time portal, the Guardian of Forever, to face her past. She briefly returned to her throne back in her home dimension and realized that she had, against all odds, developed a modicum of compassion. She was still an evil, violent murderer, but was no longer the genocidal sadist she's once been. These episodes took place during the third season of "Discovery" which, we shall see below, was set in the distant future of 3189. After this experience, the Guardian of Forever shunted her back in time to the year 2257.
The timeline of "Section 31" is a little confusing, as Empress Georgiou was sent back to the same time as the second season of "Star Trek: Discovery." That would mean that there were, briefly, two Mirror Georgious operating at the same time. A young Rachel Garrett (Kacey Rohl) is also a main character in "Section 31," and, by Trek canon, she was born sometime from 2290 to 2300. Given that she's already a lieutenant by the events of "Section 31," we can assume that it's set in the year 2324. Of course, that would mean Empress Georgiou is far older than she looks.
"Section 31" also stands apart because of its silly action plot, goofy characterizations, and non-Trek conceits. Section 31 is a spy organization within Starfleet that operates in the shadows, committing crimes on Starfleet's behalf. Empress Georgiou is asked to head a team of freelance Section 31 operatives to retrieve a doomsday device that she once built. The TV movie started its production as a series, but was shrunk to a 90-minute movie when the studio started to run low on money.