Should the app bar overlap the content?
Due to the requirements, the second app bar line contains additional information which is shown by expanding it just about the expansion panels.
Regarding the material properties the app bar is higher on the z-axis, so it could overlap the content (which would be also okay).
On the other hand when you scroll up the app bar could fade out upward, so the content affects the app bar to move with the content. Seen on this regard, the content could also move downward when expanding the app bar.
Just one of both can be implemented. I would appreciate other opinions.