From The Document Foundation Wiki
- open the Styles and Formatting window (as described above);
- select a common paragraph style like Default Style;
- right-click on the name to open the contextual menu and select New;
- in the dialog box that opens, enter a name for your style;
- click on the Indents & Spacing tab. Choose the setting under the Indent section. To get an indent of 1 cm, you need to enter 1cm in the field Before Text. Then click the First line field and enter the value -0.5cm; and
- click OK. The new style appears now among the list of styles. You can use it now as a predefined style (see above).
- If the measurement unit is set to Inch ( ▸ ▸ ▸ ▸ ▸ ), then the centimiter value you just entered will automatically be converted to inch.