iPadOS versions ongoing support

Hi everyone

I manage the fleet of iPads we have here for my company I work for.

with the iPadOS18 being released later this year, I have on the fleet iPad 5th Gen and as well as iPad 6th Gen - will these be obsolete?

I need to ensure with the OS, that security is up to date.

Or will iPadOS17 still be supported?

Do we have official Apple links to confirm this?