If you like taking pictures with your phone, the cameras are still improving steadily enough that you'll see meaningful improvements if you upgrade every three years
Plus, many people who take photos on their phone will upload it to a service like instagram/discord which compresses the photos so you lose some of the quality anyway.
The processing pipeline also started imposing its own opinions on your photos, adjusting the brightness of dark areas and bright areas to even things out, increasing saturation, etc. This has generally trended towards more processing over the years.
In a picture from a standalone camera (or an old phone back when the processing pipeline was basically just debayering, white balance, chroma denoise, and a gamma curve), you'll actually have contrast between shadows and highlights, which, when done well, looks great. When done poorly, it looks terrible (blown highlights, noisy shadows), which is the whole point of the processing pipeline -- on average (random user, random scene), you're better off reducing the overall contrast in the image with local adjustments, even if that turns some excellent photos into boring ones, because it'll turn a lot more bad photos into acceptable ones.
Part of that is due to the larger sensor which no phone is going to be able to compete with, but it’s also because it allows contrast to exist and photos don’t turn into smudge/blotch soup when zoomed in a little. Thanks to that, its photos capture mood better and feel closer to what I see (or remember seeing).
I’ve toyed with alternative camera apps (of which many exist on iOS) and those are a bit better, but still fall short of an decade+ old standalone camera.