This is not a simple answer, as we support a variety of laser systems, which would require slight, yet different settings to maximize the results from the one being used. We do not currently offer a “canvas” button, in this way.
LightBurn does provide powerful tools for image preparation and options for how you what the image output. These should help get you going:
Image Preparation - Redirecting...
Cropping and Masking - Image Masking - LightBurn Software Documentation
And the Cut Settings options for Image Engraving - https://lightburnsoftware.github.io/NewDocs/CutSettings-Image.html
And this is worth review as well.