Iconpackage icon set (.ip) is a renamed ZIP file, so there is no need to convert it to ZIP. Just rename the extension from ip to zip and extract the content should you really need it. Some file managers may even recognize it and extract it without change to the extension.
Convert IconPackager icon set file to WinZIP Compressed ZIP archive.
We have found one software suitable in our database for this conversion.
Microsoft Windows software - convert ip to zip on Windows
A compression utility that supports over 250 archive formats
Convert from ip file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.