If you see the same thing on both displays, you should start by making sure the displays are Extended instead of Mirroring ...

Sidecar in macOS turns your iPad into a second display, but it's limited to certain Macs and iPads. Thankfully, a few ...

A 13, 15, or 17-inch screen is fine for emailing or viewing the web, but when you’re gaming or multitasking, that space just isn’t enough. On the other hand, carrying around a massive desktop monitor ...