Kojima Productions announced earlier today on twitter that it is working on a new project.
https://platform.twitter.com/widgets.js#KojimaProductions confirms a new project is in development and is looking to hire the best-in-class talent to work out of our Tokyo studio. For more information on the openings and requirements, please visit our website at https://t.co/jeTGnnwLAW pic.twitter.com/StLOrxTlhg
— KOJIMA PRODUCTIONS (Eng) (@KojiPro2015_EN) October 22, 2020

What the game is, no one knows. The only clues we have thus far come from the listing on the careers page on the Kojima Productions site which mentions 3D model production of weapons, gadgets, vehicles, mechas, etc. Other than that there isn’t much else.
This will be the second game Kojima Productions has released since Hideo Kojima parted ways with Konami. The first game released by Kojima Productions was Death Stranding which was released in November of 2019.
I personally am excited by this and I am looking forward to more news about this project.