Along with the reveal of Dragon Quest XII: The Flames of Fate, Square Enix also revealed the spin-offs Dragon Quest Treasures and Dragon Quest Keshi Keshi.
While very little was revealed about Dragon Quest Treasures, it will follow Erik and Mia, who you might recognize from Dragon Quest XI: Echoes of an Elusive Age, childhood adventures of treasure hunting. Beyond that, it’s said to be a unconventional RPG, with more information, including release date and platforms, to be revealed sometime in the future. They’re also working towards a simultaneous release, though it currently isn’t guaranteed.
As for Dragon Quest Keshi Keshi, it’s a mobile puzzle game made by NHN PlayArt. Based off the trailer it looks to be a match three game, which makes sense given it’s mobile. Currently it’s played for release sometime in 2021.