I am trying to compress or pack multiple files in different formats into one. I am using c++ and was wondering if there is sth which is easy to use and preferably in one class or library. performance does not matter that much
C++ is out of scope here... it's just the language you're using. Standard Library is getting richer and better but it doesn't contain anything related to compression (and probably never will).
You can find a 3rd-party library for this, like zlib... :-) https://www.zlib.net/
You can also find for "zlib c++ wrapper" on Google if want want something "more C++"