The power button in Windows 10 is pretty powerful. Many of us might be using it just for powering on and off as we are not aware of the other things that the physical power button has to offer us. There is a little handy feature available in the Windows 10 that allows the users to turn off laptop screen by just clicking on the physical power button that you have. Check it out here
You need to define the power button in the power options for this.
Just head to the power options, you can go to the power options by simply right-clicking the battery icon on your system tray or you can also go there by going to the control panel.
Then inside the power options, just choose what the power buttons do.
Then under the define power buttons and turn on password protection, you will see some options for power and sleep buttons and lid settings.
Then here you need to set the first option which says when I press the power button, choose to turn off display from the drop-down menu.
That is it, it is that simple to use the regular power button for yourself and to make it useful for you. You can thus turn off laptop screen using your laptop power button.