Lol I just switched to Android cause I'm having those issues with my iPhone.
The grass is always greener...
For the most part I think iphones tend to run smooth long term and when they do get bogged down it's usually caused by an App IME.
Saying Android does or does not have that issue isn't 100% an accurate statement.
I find with Android that across most of their devices, updates can sometimes cause the phone to start having issues.
That being said I personally think Samsung phones get slow, and start having issues faster than other Android phones that are available.
I'd stick with a pixel for the best Android experience.
But there are other options as well that I would say are better than Samsung and won't start failing after a year of use.