can I download OS to a thumb drive

Hi I don't want to backup (external) my OS of High Sierra 10.13.1 because Sierra worked and I can use that if I need to change something. Which I have already done. I added a Translator from the Dashboard (with a suggestion from this site-Thanks)

So until I'm satisfied with 10.13.??? I thought maybe just go and buy a thumb drive and load my OS onto it. Does that make sense? Thanks.