SketchUp works on flat planes and sharp edges. A bevel (chamfer) or fillet (rounded edge) requires creating new geometry that flows around a corner. Doing this manually takes hours of push/pull on intersecting faces.
Rounds corners of any radius, works on complex geometry, and includes "donatationware" licensing.
: A more advanced version of RoundCorner specifically designed for complex 3D shapes and chamfers. How to Install and Use "Bevel" Bevel - SketchUp Extension Warehouse