Creating a bootable Microsoft Windows 10 USB installation stick:

Download the Win10 ISO file from here (UK/AU is English International):
https://www.microsoft.com/en-gb/software-download/windows10ISO

Use dd to write the iso file to the USB stick:

sudo dd bs=4M if=Win10_2004_English_x64.iso of=/dev/sd(*) conv=fdatasync  status=progress 

Alternative methods:
https://www.linuxbabe.com/ubuntu/easily-create-windows-10-bootable-usb-ubuntu
https://www.cyberciti.biz/faq/create-a-bootable-windows-10-usb-in-linux/