Sanity Check for app development idea needing Multiplayer function

Hi, to previse all of this, I am new to Swift and iOS app development.

I have an Idea for an app, however, this includes Multiplayer connectivity for up to 10 people. I have been trying to look into what would be required to run this. I am confused if I need to invest in an external server or if I can run this through GameKit or CloudKit.

Any help is appreciated.

Thank you.