TL;DR
There is no such plugin, nor should there be one.
Longer answer:
Google's indexing API is for broadcast events on videos and job postings only, as stated in their documentation (emphasis mine):
Indexing API Quickstart
The Indexing API allows any site owner to directly notify Google when pages are added or removed. This allows Google to schedule pages for a fresh crawl, which can lead to higher quality user traffic. Currently, the Indexing API can only be used to crawl pages with either JobPosting or BroadcastEvent embedded in a VideoObject. For websites with many short-lived pages like job postings or livestream videos, the Indexing API keeps content fresh in search results because it allows updates to be pushed individually.
It is not intended for people to try to artificially improve the ranking of a Q&A website.
