In case you need to separate two blocks of content by a line, the spacer block is what you are looking for.
To add a separator, click on the Add Block button and select the Separator block. Alternatively, you can start typing
/separator in a new paragraph block, then press enter.
Every block comes with unique and block-specific controls that allow you to manipulate the block directly right in the editor. The separator block is pretty straightforward so it only has the convert block type and more options control.
The separator block includes three styles, Short Line, Wide Line and Dots:
A short line separator is a simple style that looks like this:
A wide line separator is similar to the short line style and looks like this:
Meanwhile, a dots separator is a little different, and looks like this:
In addition to the options found in the block’s toolbar, you may locate the block specific settings in the editor sidebar panel. Clicking on the cog icon next to the publish button will toggle the visibility of this panel.
The advanced tab lets you add a CSS class to your block, allowing you to write custom CSS and apply styles to the block as you see fit.