In article , Sam Brown
wrote:

As I understand it, on a 35mm camera if 2 different lenses have the same
focal length then the angle of view would be the same in each case.

only if the sensor size is the same.

a '35mm camera' can have at least five different sensor sizes.

Is it the same on a smartphone (only focal length determines angle of
view) or does sensor size also affect the angle of view?

it does, the same as with any camera.