Child of Light II not currently in development
In Summer 2018 when Ubisoft announced a Nintendo Switch port for Child of Light, Ubisoft's Patrick Plourde blatantly teased a sequel to the delightful fairy-tale RPG in a tweet. The tweet shows the original Child of Light running on a Nintendo Switch, with a partially-obscured document clearly labeled 'Child of Light II' on the table behind it. However, it seems Child of Light II is not currently in production.
Talking with Video Games Chronicle, Plourde states that the document in the image was actually a four-to-five page summary of a potential prequel, focusing on childhood friends who grow apart as they enter adulthood. One inspiration for this theme actually stems from the fact that most of the original development team on Child of Light have departed from Ubisoft.
About this document, Plourde states:
"I don’t know if there’s a Child of Light 2 that is in production, Ubisoft is big, but I’m not working on it ... Right now, I don’t think there’s a Child of Light 2 being produced… I’m not holding my breath."
"I don’t think it’s the type of game that Ubisoft wants to make…The company is not an adolescent company, it is a mature company. And the other things, in terms of portfolio, it’s still supported – we ported it on Switch and we’re still selling a bunch of copies, but it’s just that right now it’s all about games as a service. We can make money out of it, but you can make more money elsewhere. That’s the problem of not being independent while making this."
You can read more at Video Game Chronicle. So it seems while Child of Light is now available on most modern platforms, it might stay as a sole passion project darling from Ubisoft.