Programs enabling conversion of the file:
If your objective is to convert the file from RAR to the file 7Z, you can use any of the applications listed. RAR to 7Z conversion process in every program intended for this purpose (so-called converters) is very intuitive and everyone is able to manage converting a file.
However, bear in mind that the list may also include programs to support and work with the indicated extensions RAR and 7Z - and not only converters. In such a case, you need to open the source file RAR and from the options available in the program, choose ”Save as... 7Z" or "Export to 7Z".