Border size? Around the edge of each pie slice? If so, no I don't think so.
I doubt you'll see a doughnut chart from Tableau - they don't offer any more information than a pie chart (equally, the multi-doughnuts are not easy to read). In many circumstances a bar chart is better than a pie (or a doughnut)
Thank you Alex. Yes I was referring to the border around each slice. I didn't think they could be formatted (other then colour) but thought I would ask to make sure.
Also - re the doughnut chart. I appreciate the feedback. It was a request from my management. I will continue to push the bar chart as the preferred view.