How to format laptop without usb?

Is it possible

Does the laptop have a CD / DVD or floppy drive?

If you want to format it completely, including the operating system, then not

There are different options:

Internal operations management - you can usually have the box set back there.
Connect the CD drive and format it using a Windows CD
Drive with a super strong magnet over the laptop for 5 minutes

Cd dvd

I want to format everything

What do you have available for external interfaces?

If you really want to completely reinstall the OS, then you already need an interface from which you can install the OS on the hard disk.

Alternatively, you can of course simply reset the laptop to the factory settings using the often available recovery partition. You can find information about this if you search for the name of your laptop + recovery on google.

Which usb is enough for it? 16 gb or 32

Then you can format the internal data medium (hard drive / SSD) from a CD with the appropriate operating system.

CD, DVD, floppy disk, second hard drive etc.