what targets can I create written in C++ in Xcode 14

Any non-trivial C++ app will need to bridge to objective-C or Swift in order to access Apple's APIs.

C++-to-objective-C works very smoothly, basically you can mix everything in one file. C++-to-Swift is more difficult.

Basically, if you have an app that uses a lot of Apple APIs then C++ is not ideal. On the other hand, if you have an app where the bulk of the code is not using Apple APIs then you can consider using C++ for the internal parts with a thin layer of objective-C or Swift on the outside.