Does any microsoft plugin or tool which embeds in microsoft word provides the following features???



1. Type-ahead search i.e full text search inside of all documents in a folder
2. Number of hits while type-ahead
3. Easy Navigation

If not, why they have not considered or any tool is not available...

For this we need to lookup for several open sources or commercial softwares

I am not sure what you mean by "type-ahead" search.
A Windows search on a folder goes after ot only file names but contents.

Example, Type any word in the search box in the link - The Table - Voice Of God Recordings

You will see the results, hits, navigation is very easy.

Looks it has been built using angular and dtSearch.

Whether a similar search is available via any microsoft word plugin or any open source plugin or tool to lookup in word documents?

You can test an add-in created by MVP Graham Mayor:

Document Batch Processes

If you want functionality added to Word itself, you will have to post a suggestion in the Uservoice forum at Welcome to Word's Suggestion Box!.

__________________
Stefan Blom
Microsoft Word MVP

Microsoft 365 apps for business
Windows 11 Professional