Only the first of those two novels is detailed in the announcement, but it sounds wonderful.
Heres the description: Piranesi has always lived in the House.
It has hundreds if not thousands of rooms and corridors, imprisoning an ocean.

Matt Squire/BBC America
Piranesi records his findings in his journal.
Then messages begin to appear; all is not what it seems.
A terrible truth unravels as evidence emerges of another person and perhaps even another world outside the Houses walls.
Piranesi is set to be published globally in September 2020.