In order to save power, can the coordinator send a PL command over the air to each endpoint?

In order to save power, can the coordinator send a PL command over the air to each endpoint?

No this is not a way to remotely change the power level.

Also, we do not allow coordinators to dynamically change the listen window for endpoints. The reason for this is that a sleepy endpoint is typically battery powered and dynamically extending the listen window in the field could unexpectedly and significantly reduce battery life. The listen window can be changed at the endpoint and finished endpoint products (such as battery powered sensors) will have the listen window set according to the needs of that application. When we create custom endpoints for clients, we set the listen window according to the needs of the system and will factor into our battery life calculations.