Jason

This plugin solves the problem of when you have long pages/posts/custom posts edit screens in the WordPress admin, usually caused by lots of custom fields or plugins. Whenever you get down to the bottom of the page you need to scroll back up to the top to press the update or publish button. This plugin solves this problem by automatically scrolling the sidebar into view as you scroll the page.

Sticky Admin Sidebar

Simple, but very useful. Still works with WP 5.2 (you should SVN an update to the readme).

Still works

WordPress plugin to stick the post sidebar in wp-admin so it's always in view

oceanwp

Amit Singh

Marko OceanWP

A simple plugin to stick anything you want. 
This plugin requires the <a href="https://oceanwp.org/" rel="nofollow ugc">OceanWP</a> theme to be installed.

Ocean Stick Anything

A simple plugin to stick anything you want.

Sticky Admin Sidebar vs Ocean Stick Anything