It is possible to use hard spaces to achieve the indentation instead, if the bare ASCII file should have the indented look also outside Emacs148. With Org’s support, you have to indent all lines to line up with the outline headers. You would use these settings149:
(setq org-adapt-indentation t org-hide-leading-stars t org-odd-levels-only t)
The first setting modifies paragraph filling, line wrapping, and structure editing commands to preserving or adapting the indentation as appropriate.
The second setting makes leading stars invisible by applying the
org-hide to them. For per-file preference, use these file
#+STARTUP: hidestars #+STARTUP: showstars
The third setting makes Org use only odd levels, 1, 3, 5, …, in the outline to create more indentation. On a per-file level, control this with:
#+STARTUP: odd #+STARTUP: oddeven
To convert a file between single and double stars layouts, use M-x org-convert-to-odd-levels and M-x org-convert-to-oddeven-levels.