create different term sets for different sites in a site collection

I can create a term set in site collection. Is there any OOB way to create different term sets for different sites.

In the structure below

Else is there a way programmatically that I can target certain terms for a site. e.g. Site 1 or Site 2 . So that the terms do not appear on the other sites.

How is the security of the term sets managed.Can we restrict the visibility of certain terms based on SharePoint groups.