GET and POST HTTP-server

I use w5500 as a HTTP-server, is it possible to change values of variables on the webpage and then update it on the microcontroller? I am able to get the values from the sensor but not change variables in the program

The link of project is using W5x00 for HTTP Server.
I think you can refer to as below link.

This is the example i am using, but i need some help. Is it possible to change a variable for example uint8_t x = 1; to uint8_t x= 2; from the webpage?