Prettyplan is a small tool I built in Javascript to help you view large Terraform plans with ease, before Terraform 0.12 was released and improved the way plans are displayed. I found the more spacious, colour-coded, and expandable visualisation quite helpful for reviewing large sets of changes.
The source is all available on GitHub, and there’s even a CLI version built with Go that generates HTML files containing the formatted plan output! However the tool has never been updated to work with the newer plan formats of 0.12+ so it’s probably not terribly useful these days.