I’m a bit confused about what you are trying to do!
Blender defaults are all based on real life physics.
So a 100watt light bulb at 10cm will be the same in blender as in real life.
Meaning to bright, strange shadows etc.
You can change Blenders start up defaults ~ not recommended!
open a new blender file. delete the cube, delete the lamp, etc.
Than just save the file. Blender will overwrite, its default template.