

Step 1: Go to Tools > AutoCorrect > AutoCorrect Options from the top menu-bar. Note: If auto-correct isn’t working, make sure to turn it on in the AutoCorrect options.

Bold Single Line: Type three underscores (_) and press Enter.Single Line: Type three hyphens (-) and press Enter.You can insert other types of lines as well using different characters, for example: LibreOffice Writer auto-corrects the hyphens with a line.Put the cursor where you want to add the line.If the auto-correct options are turned on, LibreOffice Writer would recognize the pattern and automatically replace the characters with a line.

The easiest way to add a horizontal line into a document is typing three hyphen characters and then press the Enter. Inserting a Horizontal Line Using the Shape Tool.Traditional Way of Adding Horizontal Line.
