Making a wireless lavalier microphone with ESP8266-07
WiFi is not something you can use to transmit just any modulated signal you like.

Your only access to it is as a network connection.

You will have to collect your data and put it in packages to be transmitted.  You submit those to the network stack to be sent to the receiver.  The receiver snags the data from the radio waves and passes that to your program.

It doesn't work the way you seem to think is does, but you should be able to make something work.

I doubt you will be happy with it.

The time delay for packets over wifi is generally higher than you want for live audio.  Tens of milliseconds are noticeable when you have voice and video.

Class D amplifiers are difficult to build - I suspect it will be much more difficult for what you are doing.