This has not been my experience. I can usually tell when my phone bogs down loading an intense website or switching between 3 apps after a couple years. If I want my phone to last a long time and I want to enjoy using it I've found that it's best to start with a device that is as powerful as possible.
That's usually a combination of planned obsolesence and bad software, Smasung flagships for example start to significantly slow down after roughly a year of usage. These CPUs are more than enough for daily tasks like web browsing and as soon as you have a manufacturer with good software support or load something like LineageOS on the device it usually works very well again, in some cases you also need a new battery because many clock down once that looses capacity.