It depends on what action the term “format” refers to.
Resetting your PC or reinstalling Windows from media will replace the current instance of the OS with a new and “fresh” one. You’ll still “have Windows” and a usable laptop, but most of your apps and personal files will be gone.
Formatting a secondary device doesn’t affect the primary drive with the OS.
Windows doesn’t allow formatting the OS’s primary storage device from within the OS. You can format the OS drive from “outside” the OS, for example, by using a bootable Linux distribution from a Flash Drive. As a result, you’ll “lose Windows” until you reinstall the OS. It’s impossible to fully retrieve all OS-related data to make it usable again.