Although you can repack .rpm (Linux packages) to 7-zip archives (.7z), it will do you no good if you are trying this conversion for program installation purposes. If you just want to explore the archives, you can extract them with plenty of available file managers.
Convert Linux package manager archive to 7-ZIP compressed 7z archive.
We have found 2 software records in our database eligible for .rpm to .7z file format conversion.
Microsoft Windows software - convert rpm to 7z on Windows
Popular open source file archiver with a high compression ratio
Convert from rpm file format
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned rpm to 7z. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
A free open source archive utility