How to add new search option in extended search drop down options?

Do you mean different result columns based on permissions? If so, I don't think that is really possible using one Search.

Typically to do what you ask we create as many different searches needed, combinations of results and search criteria, and then use the permissions on the searches itself to limit who can see and use them.

Hi Devang,

Do you mean, creating one eQL search for all the users with different permissions can search different documents?
If Yes, default search for document is doing the same for all the users.