If you hover over the ▶️ button, you can see a few options. Let's go over them in a bit more detail.
Here, take a look.
Tired of clicking ▶️ constantly? Enabling this option ties pressing ▶️ to your keystrokes, updating the preview area as you type. Pretty handy for larger projects, where minute detail is key.
This is a setting you can toggle on or off entirely in the Settings Menu, in the Startup Behavior section.
Separate window - This option writes your project to a pop-up window. You have complete control over this pop-up, so drag it around and resize it as you like. However, most inline scripts will not run (this is intentional). This feature is really meant to help you get a feel for your project's performance, which may be on different screen sizes and resolutions.
In-workspace - This option simply hides the code input boxes, and fills your workspace with the preview area. Now you can see your project in a near-fullscreen environment, scripts working and all.