Many forum posts promise a working portable version, but consider these dangers:
Another approach is to use virtualization software (like VMware ThinApp, VirtualBox, etc.) to create a virtual environment that can run Office 2003. This method encapsulates the software in a virtual machine or a similar container that can be considered "portable." Microsoft Office 2003 Portable Download WORK
For a straightforward download, you might look for a version that’s been made available by its creators or a site hosting old software. However, proceed with caution and only use reputable sites like Internet Archive (https://archive.org/), which sometimes hosts older software for educational or archival purposes. Many forum posts promise a working portable version,
Download from PortableApps.com (trusted source). It includes Writer, Calc, Impress, and Base. You can set the UI theme to mimic Office 2003, and it saves in .doc/.xls by default if desired. It’s fully updated, secure, and legal. Download from PortableApps
In many jurisdictions, downloading unlicensed Microsoft software is a civil offense with fines up to $150,000 per instance under the Digital Millennium Copyright Act (DMCA) or similar laws.