I can’t update my iPad to iOS 13.0

On the basis of the tags appended to your post, selected by you when submitting your question, I surmise that you have an original first generation iPad Air, an iPad mini2 or mini3. These models of iPad can only be updated to iOS 12.4.8.

Apple ended update support for these devices in September 2019. They 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.

Some App developers have dropped support for iOS versions preceding iOS 13.x for technical reasons (often because APIs or software libraries upon which they rely have been updated in the new version of iPadOS, making their App incompatible with earlier versions). 

Whilst many App titles remain compatible with your iPad, if you want or need to access to Apps requiring the most recent versions of iOS, you’ll need to consider replacement of your iPad with a newer or current model that supports iPadOS13/14.

I hope this information provides helpful clarity as to your available options - and the limitations of your existing iPad.

That is correct.

If your iPad Mini has been stuck on various versions of iOS 13, then you own a 2013, iPad Mini 2 or 2014 iPad Mini 3.

Neither of these are capable of upgrading beyond iOS 12.

The 2013 iPad Air 1, iPad Mini 2 and the 2014 iPad MIni 3 have underpowered internal hardware.

Your iPad model is too old, now.

Sorry.

If you need/want an iPad with an up to date iPadOS with access to current, updated apps, then you really need to seriously consider a new iPad model OR a much “newer” , used iPad model capable of running the latest iPadOS versions.

There are plenty of newer, older iPad models that can run the latest, current versions of iPadOS.

Sorry & Best of Luck to You!