Also plants don’t really expend energy to modulate their bodies. It’s more about moving water around their internals.
Yes, but no. The energy expenditure is there, just not in the same way as animals and motile single-celled organisms. It’s, to borrow from software engineering, “left-shifted”. Plants invest the energy into building structures in their bodies that can be actuated via environmental changes. So, for example change in temperature between day and night may change hydrostatic pressure, which in turn causes motion (opening and closing the blossom).