Call Continuity between Mac and iPhone
If I answer a call on my Mac then need to leave and transfer to my iPhone how do I do that?
MacBook Pro 14″, macOS 12.0
See this Manage phone calls in FaceTime on Mac - Apple Support
Transfer the call to your iPhone: When your Mac is near your iPhone, tap the Handoff icon that appears in the bottom-left corner of the Lock Screen of your iPhone.