I was looking for something similar, wanting to customize the formatter. The best solution I could find was to download the Eclipse IDE itself and use the built-in Formatter Profile Editor, available under Project -> Properties, then Java Code Style -> Formatter (and perhaps -> Configure Workspace Settings)

While it is very convoluted and cumbersome, it is also a much more powerful and versatile version of the "Java Formatter Settings with Preview" available in VS Code. It offers a preview of every single setting using a fitting code example to visualize the changes. It also allows for the examples to be changed and custom code to be tested with the "View/edit raw code" option and "Custom preview contents" toggle. Once satisfied, it can be exported and the resulting file be used as the projects eclipse-formatter.xml.

While it's not a 1:1 description of every setting and their respective byte combinations, I feel that it fullfills that role very well.