I was wondering if I could use a .qar format for my qlik sense extensions like with Qlikview. If this isn't possible, is there an alternative that does the same? I tried googling for auto installing files etc. but I couldn't find anything.
Sorry, there is nothing like that. You'll need a zip file for Qlik Sense server, and copying the files to My Document\Qlik\Sense\Extensions for Qlik Sense desktop yourself. For desktop you also need to make sure that there are no duplicate qext files.