What is the name of Apple's color emoji font used to render emoji on its platforms?

Apple's color emoji font is called Apple Color Emoji.

Apple Color Emoji is a font family designed by Apple to display emoji with multicolour artwork. It is used across Apple operating systems and devices, including iPhone, iPad, and Mac products.

Emoji are encoded as Unicode characters, but their appearance depends on the font and platform rendering them. Consequently, an emoji sent from an iPhone may look noticeably different on Android, Windows, or a web browser even though the underlying Unicode character is the same.

Apple Color Emoji is not the same thing as Unicode's emoji standard. Unicode assigns characters and defines relevant properties, while Apple creates its own visual designs. Other major platform fonts include Google's Noto Color Emoji and Microsoft's Segoe UI Emoji.