Generally, The implementation of the HTTP client generates and sends data according to the HTTP protocol format(HTTP request), and receives the response from server(HTTP response).
It is difficult to provide a generalized HTTP client example because the type of HTTP request packet to be generated depends on the characteristics of the server side.
I personally implemented HTTP client code was uploaded to the my Github branch. This code was implemented for the W7500 MCU, but I expect it to work with the W5500 chip as well.
When implementing with W5100 chip, socket related functions may need to be modified.
Please refer to the three files in the following link.