Antenna chains, TPC, regDB

Hi there,
I am to setup my new Netgear R7800. This device will be used with a set of small antennas (not the factory supplied) indoors. How to optimize LEDE/OpenWRT for this use?

Is there an antenna-chains setting like in DD-WRT ( Should I experiment with this and where do I find this setting?

Is TPC supported with this device? Regulatory DB only allows for 27dB on some channels, although 30dB would be allowed with TPC. If TPC is supported, how to increase tx-power over the regDB limit?

While the smaller antennas have less gain, my tx-power should even be allowed 2dB up. Where is the setting for antenna gain, when it is less than the factory default?