Hi Binu, but why you are submitting the URLs anyway ?

Google will crawl your website anyway. did you add it to Google search console?

in my experience, these simple tricks doesn’t affect your traffic, what really matters is the content of the web page.

Read the Note here on Rankmath website:

https://rankmath.com/wordpress/plugin/instant-indexing/

they state clearly:

Note: Google recommends that you use the Indexing API ONLY for Job Posting and Live Streaming websites. However, it works on any type of website and many of our users have seen great results already. Please proceed with caution.

I my self don’t recommend this.