Explanation:

Policy 1 will update 800 iOS devices that are enrolled by using Apple Automated Device Enrollment (ADE). This is because ADE devices are supervised devices that support software update policies in Intune1. Devices that are enrolled by using the Intune Company Portal are not supervised devices and do not support software update policies2.
To ensure that only iOS/iPadOS 15.5 is installed, you should configure a device restriction policy that restricts visibility of software updates. This will prevent users from manually updating the OS to a newer version than the one you specified in Policy 11. You can use the Deployment Workbench to create and assign a device restriction profile to your ADE devices3.