In principle it is possible to manage the priority in such a way that if traffic is set to a certain priority (which is not the highest one), and the coordinator sees that there is no higher priority and automatically increases the priority to the maximum possible value.
However, it is not recommended to do this for multiple devices and for long time. It can block traffic from other devices with normal priority. Please keep in mind that the MAC layer also uses a high priority for transmitting “Tone Map Response” packets and only 7 time slots (default value) are allocated for high priority contention window.