Selection and canvas bounds?

[rich2005]

A quick test and I think not without temporarily increasing the size of the canvas, otherwise plenty of error messages.
Using the simple smooth plugin, canvas size increased using crop tool (allow growing mode). https://i.imgur.com/jVukQBf.jpg
Apply to selection. https://i.imgur.com/8RhQfhn.jpg
Revert the canvas back with Image -> Crop to content. https://i.imgur.com/Z7Wd0Pa.jpg

Ofnuts will have more idea.