To earn the "SECRETS" trophy in Detroit: Become Human, you must progress through the first chapters with Connor, Kara and Markus until you reach the chapter named "A NEW HOME".
The most efficient path to this trophy is to only clean up the trash downstairs and then report into Todd when you get the opportunity, to unlock the upstairs. Clean Todd's room, Alice's room and the bathroom. Go and speak to Alice, choose comforting options. Eventually Alice will give you a key and leave. Put this key in the treasure chest on the dresser near the door. Interact with the contents before heading downstairs to finish the chapter. As long as you made sure to open the box and view the contents you will earn this trophy when you reach the flowchart at the end of the chapter.