The default transmit power of the pluto is -10 dBm. Is there any way to change this without recompile the firmware?
No. Firmware must be changed.
It needs to be set in device tree: https://github.com/analogdevicesinc/linux/blob/04618998de540e5ebcf8111969c2e1a492c50258/arch/arm/boot/dts/zynq-pluto-sdr.dtsi#L267
Thanks for your answer. To change default TX output power or turn off TX LO, which line of code should I change to ?