The Preview window exists by default as a pane on the right side of your screen. It's a live preview of your current code that auto updates whenever you stop typing. You can resize the preview, explore different screen dimensions, block images, or simulate visual impairments.
You can manually refresh the preview using the Refresh Icon button in the top left of the preview or via the command palette.
If you prefer to use the browser's built in developer tools, you can view the HTML content of an email rendered in your browser. Right click on any file in the file tree and then click Open raw in new tab.
If you like working with multiple screens, you can pop out the Preview into a separate tab.
Simply close the preview tab to restore your workspace to the default layout.