No official word as been said from SEGA, but apparently, there is a Sonic Forces: Day One Edition available for pre-order on a Spain operated website called XtraLife. This is coming from a post from the people over at Sonic Paradise.
This is available for pre-order for both the PlayStation 4 and Xbox One versions of the game. This pre-order will include costumes for the custom character from previous SEGA games such as Jet Set Radio, NiGHTS into Dreams, Super Monkey Ball, and Puyo Puyo Tetris. However, this DLC was also mentioned in an official SEGA document when they were given permission to release the game in China. It will also have four pieces of concept art in the form of postcards. Again, nothing has been confirmed from SEGA at this point.
We will have more information about Sonic Forces in the future and a possible confirmation about this Day One Edition at a later date.