Control access to posts

Hi All: Relatively new user here.

I would like to restrict specific users viewing access to specific categories/posts. I have searched the forum extensively and not found what I want (or at least not identified a plugin yet.) I have tried the Manager User Group plugin but it does not do what I want.

Four years ago Christiaan posted the request for a “Flickr-like access control for friends and family” plugin. However, I have not been able to find one, if one exists.

Does anyone know of a solution?

Thankx,
Harold