One phone in my family is a 2017 2018 flagship, and people are amazed how snappy it is (they don’t know it’s from 2018).

Its running a fork of Lineage, with 2 or 3gb of ram (I forget). Because it’s so optimized, even with a bunch of apps (~200), it’s fast and battery does pretty well.

Old phones can run fine, but they have to be managed to do so.

Edit: 2018 flagship.