1. Lower level managers usually find out them at the same time as IC's 2. Managers and directors can be part of the layoffs. 3. If a manager/director is part of the layoff, they are even less likely to be consulted in the process.
The rule of thumb is if they can't fire you they aren't really your boss.
For instance, at a previous firm, the COO, which ostensibly can be fired by the CEO was actually the brother of executor of the chief investment in the last round so the COO has a direct board connection and so he could actually fire the CEO with enough effort. Underneath the COO was a finance guy who had just come from a possible acquirer so really that guy could probably get them both fired if it meant a good payout for an acquire.
The tendrils are wacky which is why when a room of those people have to do actual work, it's not some shrewd rational calculated execution but instead just some hot mess