a) the phone displays are getting wider; with widening of the aspect ratio, the diagonal is rising faster than the surface of the display.
b) the ratio of screen to body rises (you are getting smaller bezels).
That means in practice, that for example the 5,2" Sony Xperia Z5 (with ~70% screen to body ratio, 16:9 display aspect ratio) is 1,5 mm narrower and 4 mm shorter than 6,1" Samsung Galaxy S10 (~88% screen to body ratio, 19:9 aspect ratio). Subjectively, thanks to the rounded corners of the S10, it feels smaller than Z5.
Based on the screen diagonal, you would not say that you are going to have such impression, the difference is 0,9" after all.
As you say the battle now is on to eliminate bezels. From what I can tell the final station on that journey is a screen of about 6.5" to 6.75".
its not really "top of the line" anymore, but the fact that its light on the wallet (~$250) is another major benefit
For a 3.3" smartphone check this https://liliputing.com/2019/06/palms-tiny-smartphone-now-ava...