In my experience, a LOT of company culture trickles down from the top. Some of this is by design e.g. CEO consciously and publicly rewards certain traits/behaviors. Some of this is accidental in the sense that CEOs, like many humans, have both stated and expressed preferences.

There is also this effect:

- CEO says "the lights are a bit dim in here"

- that turns into "We need to change all of the lightbulbs in here immediately!"

(this is especially true in firms where the CEO cares a lot about being proactive).

Two great posts/stories about this:

1. This post about smart employees "reading their managers minds": https://yosefk.com/blog/people-can-read-their-managers-mind....

2. In Michael Crichton's book Disclosure there is a great line: "Why did you dress casually instead of wearing a suit? Is it b/c you wanted to do that or b/c the CEO did it and you wanted to show you were part of the team??"