Can I just inject code on selected pages/posts only?

Can I just inject code on selected pages/posts only?

I see I can add code to all pages or just the home page and then remove the code (from selected pages at the bottom of each page).

But is there a way that I can just select (or list) which pages or posts that I want to have the code injected into? If so, please just let me know.

Thanks,
Gary