Paint 3D is not available for Mac but there are some alternatives that runs on macOS with similar functionality. The best Mac 3D Modeler alternative is SketchUp. It's not free, so if you're looking for a free alternative, you could try Artist3D. If that doesn't suit you, our users have ranked more than 10 alternatives to Paint 3D and seven of them are 3D Modelers available for Mac so hopefully you can find a suitable replacement. Other interesting Mac 3D Modeler alternatives to Paint 3D are ZBrush, Adobe Dimension, Autodesk Mudbox and Assetforge.
I have a Mac and I use sketch up to do models and it may even be better than paint 3D