The dates on which the movie, split into two halves, will be released in Japanese theaters are disclosed in the new Pretty Guardian Sailor Moon Cosmos teaser trailer: June 9 and 30, 2023. The two movies are the next installments in the new Sailor Moon manga adaptation that started with the animated series Sailor Moon Crystal and continues with the two Sailor Moon Eternal movies.
The story:
In the arc of Sailor Moon Sailor Stars, the fifth act, Stars, is explained in the 50–60 acts of the manga (volumes 11 and 12 of the GP Publishing edition, volumes 9–10 of the Eternal edition of Star Comics), as well as the 174–200 episodes of the animated series. The main focus of this last act is Sailor Galaxia, the new foe, who is looking for Star Seeds. There were many new fighters revealed, including the Sailor Starlights, who came from several planetary systems. Future-era Sailor Cosmos first goes unnoticed by adopting the persona of a young child named Chibi Chibi. The final two acts reveal its actual form.
Sailor Starlights / Three Lights:

In addition, the new voice actors have been announced:
Saori Hayami (Yor in SPY x FAMILY) double Sailor Star Maker
Marina Inoue (Tohka in Date A Live) double Sailor Star Fighter
Ayane Sakura (Rei in Do It Yourself!!) Double Sailor Star Healer
Confirmed the return of the other voice actors.
The staff:
The film is directed by Tomoya Takahashi (associate director of Gatchaman Crowds), while Kazuyuki Fudeyasu (author of That Time I Got Reincarnated as a Slime) wrote the narrative. Kazuko Tadano (character designer for Sailor Moon seasons 1 and 2, Eternal) also returns.
Yasuharu Takanashi, a music producer (Sailor Moon Crystal), and Yumiko Kuga, an artist (Deaimon: Recipe for Happiness).
The animation is produced by Toei Animation and Studio Deen, same like in Eternal.
We can expect that Cosmos will have an international Netflix release, similar to how Eternal did.