org-list-indent-offset

org-list-indent-offset is a variable defined in `org-list.el'.
Its value is

0

Documentation:
Additional indentation for sub-items in a list.
By setting this to a small number, usually 1 or 2, one can more
clearly distinguish sub-items in a list.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 24.1 of Emacs.