What year is my IPAD

Go to Settings ➜ General ➜ About and post the model number here.

Or if the model name field is visible, use that to search for a case.

For more details click here ➜ Identify your iPad model - Apple Support

Check Settings > General > About > [Model Name or Model Number] and report the results here.

What is the model number at: Settings - General - About - Model = ??

It should appear as below.

Or:

That is a 1st generation iPad Pro 12.9” (Cellular + WiFi).

To add to stedman1’s analysis, since you mentioned year of purchase, Apple released this model in 2015.

You are quite welcome.