There are several methods for you to access AI Lens.

From Camera

Open Camera, select Photo mode, and touch to access AI Lens.

From the Search Bar

When the screen is unlocked, swipe down from the centre of the screen to open the search box and touch next to the search bar to access AI Lens.

From the Lock Screen

When the screen is locked, turn it on, swipe up from the bottom to open the shortcuts panel, and touch to unlock the screen and access AI Lens.