There is a growing ecosystem of unofficial community-made plugins for Bevy. They provide a lot of functionality that is not officially included with the engine. You might greatly benefit from using some of these in your projects.
To find such plugins, you should search the Bevy Assets page on the official Bevy website. This is the official registry of known community-made things for Bevy. If you publish your own plugins for Bevy, you should contribute a link to be added to that page.
Beware that some 3rd-party plugins may use unusual licenses! Be sure to check the license before using a plugin in your project.
Other pages in this book with valuable information when using 3rd-party plugins: