Mortal Kombat 11 will be available to your will only and only if you decide to pre-order. According to multiple media
It is quite notable that there will be an alpha event even before we meet a beta that will be widely available to everyone.
Now that Mortal Kombat is available to pre-order on PC, Xbox One, PS4 and Nintendo Switch, a pre-order in a physical form will also grant a Beta access.
The beta version will release in March 2019, which is just a month before the official release. There will be only one character to be played with, and that is Shao Kahn.
However, according to the devs and media, there will be more cosmetics coming in the game, probably as a way to scale the monetization.