Diiferent submodules in Console and Info

After set up the normals length there is a “bpy.context.space_data.overlay.normals_length = 1” message in Info window. I would like to change the length by Console with similar command, but when I trying to use a same modules there is no space_data submodule called “overlay”.
Please, how should I procede to touch the normals? Is it somewhere in bpy.data?
(the main aim is to export normals to txt file and this would be just a step to learn to control editing by console)
Thank you.

The info panel should not be relied on, nor should operators if not absolutely necessary.

This is not setting normal length for anything other than the viewport overlay. Nothing in space_data is operating on geometry, it’s just a part of the UI.

For efficient access to geometry data you should look at bmesh.

Better yet, start here.