Extraction of incomplete .rar file

First, if the header is corrupted or the header is password protected and you don't know the password, the program has no information about the content of the archive and is therefore unable to extract files.

Extracting with unrar and the keep broken extracted files option sometimes works, but it depends on the archive contents.

unrar x -kb example.rar

Advice for sharing files: Avoid zipping, nested zipping, splitting, remuxing, etcetera.