When you configure device restrictions settings for iOS in Intune such as single app mode, or you configure feature settings such as home screen layout, you may be required to enter the bundle ID for iOS apps.
Every iOS app requires a bundle ID to work. The ID is a string that's set up during development, usually in the form com.your-company.app-name, for example, com.microsoft.CompanyPortal for the Intune Company Portal app. You can't directly look up the bundle ID in the App Store.