On a MacBook, how do I use only the external screen?

"Hi folks, hope someone can shed some light. I have a Macbook Air hooked up to a 4K LG monitor through HDMI via a Thunderbolt 3 hub. Everything works fine, but I can't find a way to turn off the Retina Display on the Macbook and just keep the external monitor as the only screen (in Windows/Linux, you can simply press Win/Super+P and cycle through Laptop, External, Mirror, Extend). Is there something similar for macOS?"