I’m unaware of the ability to change the attribution windows as you run reports in the Twitter Ads UI. You do have the ability to change the windows on your conversion events, and then export a report. But you would have to change the windows every time in order to see reporting by different window.
Therefore, no we do not provide this functionality in the Ads API either. You would have to follow the same logic, update the windows on all of your conversion events and then retrieve stats each time.