ESP8266 (ESP-12E) as HTTP Request Client and Server in an IoT project

Greetings to you.
I have chosen an IoT topic for a team project. The web is full of tutorials on how to download a GET HTTP Request to an ESP server or send such a request from it. But is it possible to combine these functions? E.g..
if (ip.esp/gpio/0 ( Pin LOW)){
send to rpi3/stangpio/value=0
(and this information is written to the DB or displayed)
else (ip.esp/gpio/1 ( Pin HEIGH))
send to rpi3/stangpio/value=1
(and this information saves DB or displays)
I have set up the server in Flash. I should add that I am using the Arduino IDE.

Thank you very much for any answer and suggestion

clean up this code to some meaningful formatting.
It is possible to combine EVERY FUNCTION.
What question, what answer.

As an aside. Sending data is done either POST (new data) or PUT (update of existing data).
GET is read-only.