To deploy a specific iOS update to the unmanaged iPad devices, you need to perform the following actions:

Enroll the devices in Microsoft Intune by using Apple Business Manager. Apple Business Manager is a service that allows you to enroll and manage iOS/iPadOS devices in bulk. You can use Apple Business Manager to assign devices to Microsoft Intune and enroll them as supervised devices. Supervised devices are devices that have more management features and restrictions than unsupervised devices. You can also use Apple Business Manager to create device groups and assign roles and permissions12.

Create a device configuration profile. A device configuration profile is a policy that you can create and assign in Microsoft Intune to configure settings on your devices. You can use a device configuration profile to manage software updates for iOS/iPadOS supervised devices. You can choose to deploy the latest update or an older update, specify a schedule for the update installation, and delay the visibility of software updates on the devices34.

The other options are not correct for this scenario because:

Enrolling the devices in Microsoft Intune by using the Intune Company Portal is not suitable for unmanaged devices. The Intune Company Portal is an app that users can download and install on their personal or corporate-owned devices to enroll them in Microsoft Intune. However, this method requires user interaction and consent, and does not enroll the devices as supervised devices5.

Creating a compliance policy is not necessary for this scenario. A compliance policy is a policy that you can create and assign in Microsoft Intune to evaluate and enforce compliance settings on your devices. You can use a compliance policy to check if the devices meet certain requirements, such as minimum OS version, encryption, or password settings. However, a compliance policy does not deploy or manage software updates on the devices6.

Creating an iOS app provisioning profile is not relevant for this scenario. An iOS app provisioning profile is a file that contains information about the app and its distribution method. You can use an iOS app provisioning profile to deploy custom or line-of-business apps to your iOS/iPadOS devices by using Microsoft Intune. However, an iOS app provisioning profile does not affect the software updates on the devices7.