How to set tx power in gateway using Chirpstack OS

I am using RAK2245 as a gateway with RPI via Chirpstack OS.

RAK2245 is working on 27dB tx power but I want to configure it to 8dB, I couldn’t find any setting for that on Chirpstack GUI.

Can you please tell me how and from where I can configure tx power?

Please see the chirpstack-network-server.toml configuration for this.

I have seen that file located in /etc/chirpstack-network-server/ but there is no option regarding tx power. So I have also tried chirpstack-network-server configfile > chirpstack-network-server.toml command to load new config file but how can i edit that file?

Please see for the full configuration example.