I'd suspect the average person won't notice much difference (on the main lens) until about iPhone 11 or older, with still photos. Computational image processing does a TON of heavy lifting with these tiny sensors.
With video OTOH, the improvements are much more noticeable. I also suspect that is why Apple focuses so much on video as its a harder problem to solve and so much easier to differentiate your hardware from competitors.
With video OTOH, the improvements are much more noticeable. I also suspect that is why Apple focuses so much on video as its a harder problem to solve and so much easier to differentiate your hardware from competitors.