It depends on your definition of “using your iPhone through the Mac.”
If you meant having the iPhone screen mirrored and fully functional on your macOS desktop, the answer is no.
But Apple have continuity features like handoff. Example, you were browsing this site on the iPhone using Safari. In the Mac, you will see a handoff icon on the most left on the dock. Clicking on it will start safari on the exact site you were on the phone.
And to answer your next question, if both your phone and Mac use the same iCloud account, yes, you can make phone calls on the Mac, and it uses the iPhone to transmit/receive the call.
Here are the info from Apple webaite
Continuity features make it seamless to move between your Mac, iPhone, iPad, Apple Watch, Apple TV, and Apple Vision Pro devices that meet the system requirements.
support.apple.com