Creating a POST request endpoint using Element API
You might want to check out this plug-in:
Restful Api

Restful Api is a plugin for Craft CMS that exposes elements as resources via a restful api. While similar to Craft's own Element Api plugin, Restful Api offers a few more features such as support for more HTTP verbs, authentication and element type based permissions.
Restful Api utilizes Fractal to transform and serialize responses. Restful Api is also PSR-7 complaint. Its request and response objects can even be utilized by third party plugins if desired, although this has not been extensively tested yet.