Here is the full updated tutorial on how to setup Rank Math Instant indexing for Google Plugin. This process might take you some time but it really worth it as it will do your site something really good.
Important links:
0:00 Introduction to Instant Indexing
1:50 Installation of required plugins
3:40 Create an Indexing API project
6:55 Create a Service Account
11:05 Add service email to Search Console
13:01 Create JSON key
16:05 Configure Instant Indexing Plugin
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