How to manually latest update of my ipad

The tags appended to your post suggest that you have an iPad mini2/3, with iOS12 installed.

Whether or not you are able to update your iPad to a newer version of iOS/iPadOS will be dictated by your iPad model - and the currently installed version of iOS. You can find this information here:

Settings > General > About

Not sure which iPad you have? Identify your iPad model.

Here is a list of the highest version of iOS supported by the older models of iPad (for simplicity - “generations” are shortened to a number) that are restricted in their ability to be updated:

iPad1 - iOS 5.1.1

iPad2, iPad3 and iPad mini1 - iOS 9.3.5 (WiFi Only models), iOS 9.3.6 (WiFi & Cellular)

iPad4 - iOS 10.3.3 (WiFi Only), iOS 10.3.4 (WiFi & Cellular)

iPad Air1, iPad mini2 and iPad mini3 - iOS 12.5.4

Newer models, not appearing in this list, are all able to be updated to the current version, iPadOS 14.8

If your iPad is capable of being updated to a more recent version of iOS/iPadOS than is currently installed, these support pages outline both the available methods by which the update can be performed - and troubleshooting should you experience difficulties:

Update your iPhone, iPad or iPod touch – Apple Support

If you can't update or restore your iPhone, iPad or iPod touch – Apple Support

If your iPhone, iPad or iPod touch won’t update - Apple Support

iOS update and restore errors – Apple Support

The first generation iPad Air, iPad mini2 and mini3 can only be updated to iOS 12.5.4. With this version installed, you will have one of these three models.

Apple ended major update support for these models of iPad in September 2019 - although they since continue to receive “point” security updates - the most recent being released just a few weeks ago. These devices cannot be updated to iPadOS 13 (or any later major versions of iPadOS) as the internal hardware does not meet the minimum technical requirements (CPU and RAM) for newer versions of iOS/iPadOS.

The iOS/iPadOS 14.8 release addresses a specific security vulnerability that is not exposed in iOS 12.x.

I hope this information provides helpful clarity.

Given that your device is within its twilight period of update support, you might be well advised to consider replacement with a more recent device - in so doing benefiting from both enhanced functionality and full update support.