I mean, that's what people claim is what sold them on a new phone, but I can't really tell the difference anymore. Looking back at my old pictures, I can't tell when I upgraded phones. Even pictures from 2016 look amazing.
I can definitely tell a big difference in colors and details (sometimes a tad too much) from a 2016 iphone 6 to a 2020 Pixel 4 eg. But the jump from the Pixel 4a 5G to the 6 Pro wasn't that big, maybe 10-20% subjective improvement. I expect the new generation's improvement to be even more marginal and won't update.
iPhone 6 launched in 2014
Correct, it was the iphone 7 that launched in 2016. Iphone X or thereabouts hits about the sweetspot for me.