This will really, REALLY depend on each device and manufacturer.
I have Poco X3 Pro. It also has 120Hz so almost everything seems fast, but there’s some components that just seem to run at lower frame rate. For example per-app dark mode settings menu. And it’s also really buggy. But that’s expected from MIUI.
I’ve had Moto G5s Plus (2017) that was extremely laggy on Android 8.1. Then I put PixelExperience 11 (Android 11) on it and it was mostly smooth. Some manufacturers are just shitty with optimizations.