iPad update

You have an iPad Air first generation of the Air models. It is eligible to run iOS 12.4.2. I would say that millions of people are running iOS 12.4.2 on their Air's without issue. I cannot guarantee you won't have an issue though as there are some who do have issues. The processor in the first Air is a slower processor than the current iPad's and the ram is also low. What you might see is some slowness if you update, especially if you are running low on memory on a 32GB device such as yours.

You might want to give thought to upgrading your iPad after all these years. The new devices are 64 bit and the features available in the newer devices are amazing.

There is no such device as iPad 8. What model iPad do you actually own? Settings > General > About > Model

12.4.2 is highly recommended because it is currently the last version for your first generation iPad Air.