For those who purchased the original digital version of Sonic Mania on consoles and PC, an Encore DLC pack will be available for sale digitally on July 17 to upgrade to Sonic Mania Plus. (seganerds.com)
Sega confirmed that owners of the game's original digital version can pay for an unlock of the Plus content, though the company was not ready to confirm a price. (sonichq.net)
«For all gamers who purchased the original digital version of Sonic Mania on console and PC, an Encore DLC pack will be available for sale to access the new features, with more details to come at a later date.» (gamewatcher.com)