Emacs/docs/latest/emacs/Enriched-Justification

From Get docs

25.14.6 Justification in Enriched Text

In Enriched mode, you can use the following commands to specify various justification styles for filling. These commands apply to the paragraph containing point, or, if the region is active, to all paragraphs overlapping the region.

M-j l

Align lines to the left margin (set-justification-left).

M-j r

Align lines to the right margin (set-justification-right).

M-j b

Align lines to both margins, inserting spaces in the middle of the line to achieve this (set-justification-full).

M-j c

M-S

Center lines between the margins (set-justification-center).

M-j u

Turn off filling entirely (set-justification-none). The fill commands do nothing on text with this setting. You can, however, still indent the left margin.

You can also specify justification styles using the Justification submenu in the Text Properties menu. The default justification style is specified by the per-buffer variable default-justification. Its value should be one of the symbols left, right, full, center, or none; their meanings correspond to the commands above.