You can create an install image for Windows 10 by downloading the Windows 10 media creation tool (look for the Create Windows 10 installation media heading on the site). Run the program and wait for it to Get things ready. When asked What do you want to do? select the Create installation media option. Uncheck the Use the recommended options for this PC option. I’d suggest using the 64-bit version of Windows since most software is 64-bit these days.
If you want to make a bootable USB key, pick that option and use an 8GB or larger USB drive.
If you want an ISO image to install on a Virtual Machine, choose the ISO file option, and save the ISO to a directory you will remember like C:\ISO. It may take a while to get the ISO, it is around 4.5 GB.