Different sidebars or widget areas in the footer, for different posts or categories, is a very cool and in my opinion overlooked possibility in WordPress. It allows for more dynamic and relevant content in the posts, a feature that’s normally only available in premium theme builders.
Demo
Instead of a typical sidebar, I created a custom widget area, and assigned it to the footer for this specific post – effectively replacing the “related posts” widget. Sidebars and other widget areas can contain all sorts of content, including HTML and JavaScript, effectively making Content Aware Sidebar a kind of “poor man’s hook”.
Extract from WordPress.org
You can optimize conversion rates, boost on-site SEO, upsell products, and much more by displaying different widget areas on different conditions. Replace your theme sidebars on different conditions, or insert widget areas with shortcodes. With the All-in-one Sidebar Manager, you can easily activate and deactivate widget areas, and you can even schedule them for specific times.
https://wordpress.org/plugins/content-aware-sidebars/