While not "portable" in the running-from-USB sense, you can using Microsoft’s official Office Deployment Tool.
Unofficial portable versions may be bundled with malware or spyware. Always use reliable sources and scan files before opening. microsoft-office-2019-portable
Unlike standard installations that distribute files throughout the Windows Registry and system folders, portable apps run within their own isolated environment. While not "portable" in the running-from-USB sense, you