ESP8266 Community Forum

I am trying to assemble an external antenna designed by me on the ESP8266-07 wifi module, for which some changes on the chip have to be made. I want to know, in detail, what changes to be made in the hardware so that I can operate the external antenna.

I do not think you need to make any change 'inside the chip'. The difference will be in your PCB. Here is one article that you may find helpful:
https://www.instructables.com/External- ... r-ESP8266/