Add leaderboards to an app version - Configure Game Center - App Store Connect - Help - Apple Developer

Leaderboards can be added to your app version once configured. For information, view Configure leaderboards.

Enable an app version for Game Center - Configure Game Center - App Store Connect - Help - Apple Developer

Game Center and Leaderboards for Your iOS App

app store - iOS App submission is rejected as using Game Centre Leaderboards and Achievements but has not submitted for review - Stack Overflow

Configure achievements - Configure Game Center - App Store Connect - Help - Apple Developer

Integrate Game Center Leaderboard Using Game Kit Framework in iOS 7

Configure leaderboards - Configure Game Center - App Store Connect - Help - Apple Developer

What Was Game Center and What Happened to It?

Apple kills the Game Center app, but the service will continue

Developers Can Now Delete Fake Scores from Game Center Leaderboards - MacRumors

Apple Game Frameworks and Technologies: Build 2D Games with SpriteKit & Swift by Tammy Coron

How to Implement a GameKit Leaderboard in SwiftUI

Integrate Game Center Leaderboard Using Game Kit Framework in iOS 7

Configure achievements - Configure Game Center - App Store Connect - Help - Apple Developer

Game Center is getting an update! : r/ios

Configure leaderboards and achievements - Configure Game Center - App Store Connect - Help - Apple Developer