This may reduce dithering however you will end up with quite saturated colours though.
In Accessibility settings turn on the Blue/Yellow filter and increase the intensity to around 70-75%.
You can check how much dithering has been be reduced by jumping to the following site
https://appleinsider.com/articles/1...will-lead-to-more-faithful-color-reproduction
I am not able to see the logo in the red box on my original SE. On the new SE it is clearly visible. However my enabling the colour filter on the new SE the logo disappears. Not sure if this reduces dithering but maybe be worth a try even on the OLED iPhones.