you can use a live USB - you run linux off a USB Thumbdrive as a test. Ubuntu would be a good place to start: https://ubuntu.com/tutorials/create-a-usb-stick-on-windows#1-overview
There's a big ol scary warning before entering the installer and before any changes are made to your HDD/SSD, it would take a lot of mistakes in a row to somehow erase Windows by accident while using the Live USB.
it's all sixes and sevens, yeah baby