If you want to add emphasis to a piece of text in your post or page, the pullquote block can quickly and easily make short snippets look beautiful.
Get started by clicking the + Inserter icon at the bottom-left corner of the screen and select the Pullquote Block from the blocks list
Once you add the block, you type the text and author. In order to reveal the block toolbar, you can click on the block and the toolbar will display. Each block has its own block-specific controls that allow you to manipulate the block right in the editor.
How it looks like on your site will depend on the theme you have active. Different themes display different layouts for blocks.