How to choose a 50 Ohm RF attenuator for radio, bluetooth and wifi power measurements
The typical P_EIRP of standard wifi/ble/zigbee networks is in the range of 0dBm to 10dBm. This is the equivalent output power of an isotropic ratiator. 

If you have a distance of (only) 1m in between a wifi/ble/zigbee sender and your receiving meter, the attenuation of air will be around -40dB at 2.4GHz.  

Given that you have mostly isotropic radiators with little antenna gain, your receiving power will be about max. -30dBm at 1m distance to the wifi/ble/zigbee sender. 

So you can safely do wireless measurements with your power meter without worrying about the power limit. But you should not wire the power meter directly to a  wifi/ble/zigbee source without attenuator.