Keep this USB offline. Never connect Windows XP to the internet. Use it only for retro gaming, embedded machine control, or virtualization learning.
Since Microsoft no longer hosts the full OS download, users typically source original retail or volume license images from the Internet Archive (Archive.org) , which hosts several "official" untouched Microsoft ISO uploads. Keep this USB offline
If you're looking for a detailed guide or paper on creating a bootable USB drive with Windows XP SP3, I can suggest some resources: embedded machine control