How can I create a plugin for the ChatGPT

I previously noticed a ‘Develop Plugin’ option in the ChatGPT plugin section, but it seems to be no longer available. I am interested in creating a plugin for ChatGPT that sends requests to APIs and processes the responses. How can I develop and integrate this plugin into ChatGPT under these circumstances?

You can still develop plug-ins but they are now called “Actions” as part of the Custom GPTs.