Create an Offset Buffer with Corrected Radius Values
Jeff Bartels of Autodesk demos how to employ the OFFSETGAPTYPE system variable set to 1 to generate corrected offset radius buffers from any line segments in any AutoCAD 2015+ based product.
From the Jeff Bartels YouTube Channel.
and the Civil Immersion blog.
Set OFFSETGAPTYPE to 2 to champher segments at their projected intersections.
The perpendicular distance from each chamfer to its corresponding vertex on the original object is equal to the offset distance. As Jeff shows - Remember to reset the OFFSETGAPTYPE system variable to 0 or you may drive yourself and others to distraction later.