This article I read(link below) says that their could possibly be a DOA6 demo before launch. Shimbori said "He’d like fans to be able to get a taste of the game, so initiatives are being considered so that they can “touch something” before launch."
https://twinfinite.net/2018/12/dead-or-alive-6-demo/
https://twinfinite.net/2018/12/dead-or-alive-6-demo/