There’s a firmware update for the Aqara P2 motion sensor, version 1.0.3.0. While it doesn’t mention the cool down period, it allows to change the sensitivity, although probably not in SmartThings yet. (edit: in a screenshot of the Aqara app in that post you can change the cool down time, don’t know if it’s a standard Matter attribute or custom though).
I don’t have the device so I don’t know if you’ll be even able to update it with SmartThings, they’ve been radio silent for a couple years when it comes to Matter OTA updates. You can always use multi-admin with a virtual machine with Home Assistant to update it.
The Matter 1.4 sensitivity setting seems to be supported for some devices in stock drivers but not motion sensors.
Given it’s a WWST certified device, maybe @nayelyz or @Itati can suggest enabling the firmware update through SmartThings if it isn’t available and add support for the sensitivity settings in the drivers.