The WordPress Core Development team has published the WordPress 5.6 Field Guide. This is a good document to review as you prepare for the release of WordPress 5.6 in December.
This release includes the features that were released in versions 8.6 to 9.32 of the Gutenberg plugin. There are some significant improvements, but many of the new Block Editor features originally targeted for this release were deferred.
Here is a summary from the Field Guide of the highlights of this release.