All workplaces are different and there are variations of behavior within a given employer. While many have formally stated value or principles, there are typically unstated expectations that govern what is permitted and what is not.
When openness to extended work and flexible and phased retirement exists, there is ideally a set of principles or assumptions for the behavior of employers and employees that encourage successful outcomes. These mark the spirit in which you should consider any proposal.
In the course of proposing and negotiating different ways of working, it is helpful to determine if you are comfortable with these principles. You may also choose to discuss them with your manager to clarify the basis on which you hope to proceed.