Yes, they have sloped ceiling boxes and sloped fan adoption kits, available pretty much in any Box Store or a Light Store.

And you need to know the degree of pitch. .......: ) Not all are equal. Nor are the adaptor kits.

Slope adopter kits are Angel up to 45° roof angle which will work with any sloped ceiling up to 12/12 pitch.

You need to know the slope so you can size the fan down-rod.

So if your ceiling slope is:

14-18" you need a min 12" down-rod.

22-26".............................18" down-rod

30-33".............................24" down-rod

37-45".............................48" down-rod

Given this is an ATTIC........be prepared to have an issue. And buy a box fan. or window air conditioner : )