Can this device get 13.5

The original “first generation” iPad Air cannot be updated to iPadOS 13.x as it lacks the necessary minimum specification to support the newest version.

Major update support for iPad Air ended in September 2019 - the final supported version of iOS being iOS 12.4.8.

If however you have an iPad Air2, or the current iPad Air3, then you should be able to update to iPadOS 13.6. As these models are upgradable to iPadOS 13.x, whose release precedes the final iOS 12.4.8 release, the final iOS 12.x release will not be found on either Air2 or Air3 models.

As such, with an iPad Air1 it cannot be updated further. If Apps that you need require iPadOS 13.x, then you have no alternative other than to replace your iPad with a newer model.

Hi, welcome to the Apple Users Community.

Please try this link for help with your issue

https://support.apple.com/en-us/HT211168

There are also updates to 13.51 and 13.6 available within the links on this page

https://support.apple.com/en-us/HT201222

I am not certain if these have any iMovie updates.

Best of luck

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