Chrome User-Agent Spoofing Script

I’m looking for a clean, repeatable way to spoof only the User-Agent fingerprint that Chrome exposes so my automated traffic appears to come alternately from Windows and macOS machines. Here’s what I need:(spoof browser fingerprints to evade detection)

• A script, browser extension, or wrapper compatible with the latest stable Chrome that lets me programmatically set any User-Agent string I supply.
• Straightforward switching between Windows and macOS variations—no reboot or profile rebuild should be required.
• Operation in both headless and normal Chrome sessions without breaking websites that probe for automation.

Deliverable
A tested solution (source code plus concise setup notes) that I can drop into an existing automation flow. I’ll verify success using public fingerprinting sites and expect to see the exact User-Agent values I pass through your tool.