How can I make a blog private?

someone may know better, but I don’t know of a way to make a section private – individual pages, yes – whole blog, yes

maybe you could just install another instance of wordpress in a folder for employees, etc. then just make the whole blog private for this folder
https://www.ads-software.com/extend/plugins/private-only/

https://codex.www.ads-software.com/Installing_Multiple_Blogs

I know of the private-only, membership, members, absolute-privacy and permission plugins, but couldn’t find a “private-section” plugin.

With a separate WP install I sacrifice on SEO capabilities and Google Analytics data, and add unnecessary maintenance. Sure, a WP network could be an option.