Refer
Plot
Area for other formatting options.
The formatting for the radius options in Pie/Donut charts can be done using
Radius formatters in Plot Area formatter for respective charts.
Donut Chart Radius Formatter:
The 2 formatter options are available - The Donut Outer Radius and Donut
Inner Radius. The values entered are in the range of 10-100. These values are referred
in the unit of %.
This refers to the percentage of available area of Plot Area.
The Radius is adjusted as per the requirements.
Similarly for Pie chart, the formatter option – Pie Radius- is available in
the Plot Area formatter of Pie Chart.

Pie/Donut chart radius is adjusted to fit/adjust the available chart plot in
the Plot Area.