Stepu.7z -

daemondevin/7-ZipPortable: A portable build of 7-Zip ... - GitHub

Can be converted into an .exe file that extracts itself without needing the 7-Zip software installed. Stepu.7z

Combines multiple similar files into a single stream to achieve even better compression. daemondevin/7-ZipPortable: A portable build of 7-Zip

If you are looking to create a "feature" (functional enhancement) for a project contained within this archive, or if you meant to ask about features for the format itself, here are the standard capabilities and ways to work with it: Common Features of 7z Archives Stepu.7z