Software update
I bought my iPad 6th gen on January 11th of 2019. I’ve received all the updates except the iOS15. When I go to settings and tap on ‘software update’ it shows ‘ iPadOS 14.6’ & ‘ iPadOS is up to date’.
iPad, iPadOS 14
The official Apple release of iPadOS 15 won’t be until sometime in the Fall of 2021.
Your iPad is, currently, up to date.