Hello, If you have already configured your IAPs and offers in App Store Connect, you can build and run your app on a physical device and test in the Sandbox environment (note that this requires logging in with a Sandbox account). If you prefer to use the simulator instead, check out StoreKit Testing in Xcode: https://developer.apple.com/documentation/xcode/setting-up-storekit-testing-in-xcode. This allows you to setup a local test environment for testing your IAPs (including offers). You can set up a StoreKit configuration file manually, or have it sync with your App Store Connect account so you can test with the same data you have already configured. If you have any questions regarding this setup, don't hesitate to ask.
Topic:
StoreKit
SubTopic:
StoreKit, In-App Purchase, and App Store Server API Q&A