If I have Apple Care Plus and I lose my phone, do I get a new one free of charge?

Welcome to Apple Support Communities.

No.

If you have AppleCare+ with Theft & Loss, you may have a reduced replacement cost: File an iPhone Theft and Loss Claim - Official Apple Support.

If you didn't have AppleCare+ with Theft & Loss, there is nothing you can do except read: If your iPhone, iPad, or iPod touch is lost or stolen - Apple Support.

-Jack

No. AppleCare+ reduces the cost of replacing lost units and accidental damage incidents, but doesn't eliminate it.

(201619)