Expo and ExpoKit is not quite the same.
If you just start a project with
expo init you have a project which can be run with Expo Client app on the phone etc. but for that reason you cannot add any 3rd party library containing native code.
If you eject to ExpoKit you end up basically with a React Native project with Expo SDK as a library. There are bunch of consequences (https://docs.expo.io/versions/v31.0.0/expokit/eject#should-i-eject-to-expokit) but at that point you can add 3rd party libraries with native code.
Ejecting from ExpoKit would be basically removing any references to Expo SDK and removing ExpoKit from your dependencies.