Is it possible to set public to false for the native WordPress blog

I am using my WordPress posts to generate excerpts to go to an outside URL instead of the permalink. I know how to set a custom post type's: public = false but I don't know how to do this for the native WordPress blog. I don't want a permalink page generated because I don't want duplicate content. Is there something I can add to the functions file for this?

Also, I'm not sure if I should be using publicly publicly_queryable to false for this instead of public.