This article explains how to transfer (copy) apps from iPhone to iPad on devices running iPadOS 15 or iOS 15 and later.
How to Sync Apps from iPhone to iPad
If you're buying your first iPad, it's best to transfer apps during the setup process. To transfer apps from your iPhone:
The restore feature during the installation process does not actually copy the apps from the backup file. Instead, it re-downloads them from the App Store. This process saves you from having to download the app manually.
If you’re not setting up a new iPad, you’ll need to download the app manually from the App Store. It’s free to download an app to multiple devices, as long as those devices are registered to the same Apple ID.
