While San Francisco is the modern standard, Apple’s presentation typography has shifted over the decades to match its broader corporate branding:
Apple uses as its primary font for all keynote presentations. This is the same system font used on iPhones, Macs, and Apple Watches.
Briefly, during the transition to the "flat" design era of iOS 7, Apple leaned heavily on Helvetica Neue in its slides before developing its own typeface. Key Characteristics of the Current Font
