Bluetooth power standard values
You need special software, tool, etc to operate your Bluetooth device however you want. Usually, these required components are supplied by the manufacturer of the chip used in the Bluetooth device. By the help of software, you can easily change the rf output power.

To measure connection quality, you need a companion device that communicates with your Bluetooth device and makes you enable to see PER (Packet Error Rate), BER (Bit Error Ratio) or BLER (Block Error Ratio). 

If you have all of them, just measure the connection quality by using different Rf outpower levels and decide the minimum RFoutpower level to communicate well. 

Please don't forget companion device is generally called as communication tester.