Your blog category
[DEMO] Top of something with blocks
This post has disabled output of Featured image in the Post settings. But you can use also pages for such purpose
[DEMO] Top of something with side sticky table of contents
You can add some content for the title area in Post Excerpt panel which you can find in right blocks of post
[DEMO] Top of blocks with Side contents
You can add rh_side_contents shortcode as sticky widget. Check documentation about auto contents shortcodes