Converting RAR files to SKP file

Can a RAR file be converted to a SKP file?

No.
However, newer SKP files are a special kind of ZIP file, so if all of the constituent parts are there renaming between ZIP & SKP will work…
A RAR file is a compressed file, similar to [but not the same as] a ZIP file.
If you extract the RAR file’s contents [using a RAR or compatible ZIP app] what do you get ?
If someone has sent you a SKP that has been compressed as a RAR file that should work.
Windows has built in ZIP tools, but there are also more flexible and free ZIP and RAR apps available…

Open a RAR file with Winrar

WinRAR archiver, a powerful tool to process RAR and ZIP files (rarlab.com)

See what is inside - I assume you are hoping for an SKP that someone has sent?

sorry for late reply

thanks very much for the responses