In WordPress 5.5, the block editor introduces a new concept called block patterns. The goal is to allow users to build and share predefined block layouts, ready to insert and tweak more easily.
You can find the registered block patterns on the block inserter and add them to your post/page like any other block.
Block Patterns Registration
WordPress 5.5 comes with a number of built-in block patterns but it’s also possible for third-party plugins and themes to register additional block patterns or remove existing
