https://www.cnet.com/news/your-samsung-galaxy-phone-may-power-two-screens-at-once-with-dex-dock/

The Samsung DeX dock lets you hook up your Galaxy phone to a monitor for a PC-like experience. But what if that monitor isn't enough screen space? Well, Samsung may be working on something for you.

Samsung DeX is reportedly getting dual-screen support, industry blog SamMobile reports. A new dual-screen mode will apparently give you the option of using your Galaxy device as a second screen in conjunction with the monitor. Right now your phone goes black when using the DeX dock.