I agree with nimblegorilla: an employee that fires himself does not make sense. HR fires them, or some other entity, whichever has the power and permission, does so.

In the end, no matter what example you will pick it will always have the same kind of problem, that a higher entity is needed. And in the cases where that is not true, no encapsulation is needed. For example, "employee.age()". You can just do "olderEmployee = copy(employee, age = employee.age + 1)" (pseudocode) from the outside by having the age exposed (which is not classical OOP at all).

But I'm curious if you can find a counter example. Usually it stops working when global constraints come in.