Now, I just want to know is there any plugin available that helps us to enable this feature for our website as well. Please guide us.
To answer your specific question, the site search on Google uses the RankMath SEO PRO (paid) plugin.
But… it’s important to understand what’s going on here, and under what scenario Google may display or not display a star rating in search results.
This is what the Google Product Experts tried to draw your attention to, which, unfortunately, you did not find “satisfying”… even though this is coming from the very same Google Rich Snippet documentation page that you provided here!
There’s a big difference between a star rating/review of a business or organization, versus rating for, say, recipes on the organization’s website or an online directory website providing reviews of other websites/businesses.
In essence, for a local business or organization, Google only displays ratings from 3rd-party sources. Eg, for a hotel, Google will display (sometimes aggregated) ratings from hotel review sites like TripAdvisor, Expedia, etc. But Google will not pick up the rating for the hotel provided by the hotel itself, and the reason should be obvious!
Just think about it: if any business could make up whatever rating they want for their business, wouldn’t that defeat the purpose of the feature completely?
Let me quote here the important Google policy that was pointed to you on the Google product forums:
If the review snippet is for a local business or an organization, you must follow these additional guidelines:
— If the entity that’s being reviewed controls the reviews about itself, their pages that use LocalBusiness or any other type of Organization structured data are ineligible for star review feature. For example, a review about entity A is placed on the website of entity A, either directly in their structured data or through an embedded third-party widget.
— Ratings must be sourced directly from users.
— Don’t rely on human editors to create, curate, or compile ratings information for local businesses.
In short: Google will not display a star review of your business created and supplied by your business, and no plugin is going to help you in this regard. You need to get reviews from trusted 3rd-party sources that Google can pick.
Google may, however, pick up… for example… user ratings of different recipes, fun places to visit, etc published on the same organization’s website. If you click through to the TheFunEmpire page from your SERP and examine the code, you’ll see the star rating is for the PLACE indicated in the schema code, not for the organization itself. Arguably, they’re gaming the system… but that’s a different conversation.