Personally I wouldn’t do it. To much voltage to play with like that for me. The esp8266 is only a 5V chip? So you have to have a power transformer in there as well. You will also need a 100-200 Watt solid state relay in there, and what are you going to use to control them? You will need some type of microcontroller won’t you? To put that in a breakout box somewhere would be one thing. To try and make it fit in a in-wall electrical box, I think might be a bit dangerous. When it comes to my house and family, I’m going to stay as close to standard products as I can. The risk is just to great.
Everything can be done on the esp, out to a mechanical or solid state relay of choice. AC Electrical components in required safety box with the 3.3v lead into it from the esp to trigger the relay and your all good.
Been running this type of setup for a few years now controlling space heaters, lights, fans etc.
Putting it into a wall box, thats another story. It is being done. I’ve seen boards on tindie.com for esp wall box gadgets
I just saw these esp 4 channel relay pop up on ali. A suitable box with 2 duplex sockets and you’ve got a 4 way outlet box.
These are some of the esp gadgets around the house.