New IPad Air

No, you won't be able to use an OtterBox case and use the Smart Folio Case at the same time.

There are however some options which will work:

https://www.amazon.com/s?k=ipad+air+3+back+cover+compatible+with+smart+keyboard&crid=ZO8GNL8RCTM6&sprefix=ipad+air+3+b%2Caps%2C153&ref=nb_sb_ss_i_6_12

If protection is important to you, perhaps the Smart Folio Keyboard is not the best option for your Air.

There are loads of Bluetooth Keyboards (they won't use the smart connectors, but will work just fine) you can purchase from Amazon. They will most assuredly provide more protection than the Smart Folio and include things the Smart Folio doesn't offer, such as backlit keys and iOS shortcuts.

Here is a link to some options:

https://www.amazon.com/s?k=ipad+air+3+bluetooth+keyboard&crid=2F6RVLG3DUOG6&sprefix=ipad+air+3+bluetoo%2Caps%2C151&ref=nb_sb_ss_i_1_18