While the plugin API docs are a bit opaque, the original post is completely batshit crazy and nothing in the plugin docs suggests that any of that should be possible. And, none of it is.
@josh.mamroud, none of the plugin APIs (client side element, client side action, server side action) can create nor can they modify Things (including a User, which is just a system-level Thing).
What @doug.burden says is true, but such approaches are application-specific, and if you’re trying to build a generically-useful plugin for the marketplace (vs a plugin specific to your own app) this can be quite challenging (e.g., you’ll have to provide a means for the Bubble programmer user to tell you about their endpoint(s) in question).
What I mostly wanted to stress is that (1) the plugin APIs do not allow us to create or modify Things programmatically (this can only be done by the Bubble programmer user via the create and make changes to Things actions) and (2) if you see some hint or implication that this is possible (e.g., in an old forum post, incorrect information from Bubble support, or a hallucinated idea from ChatGPT), please refer to point (1).