Ignore any notion of "cycles" when it comes to battery life. Modern batteries don't suffer from progressive death like they used to. These days, you can charge your phone as often as you like to whatever level you want to. The battery will certainly last longer than the time you'll have the device.
Just let it charge overnight, nothing bad will happen to it.
While this may appear to be true for people who purchase new phones at least every 2 years, some every year, it's not always true. Batteries can still be abused to the point that you will definitely notice the cycles. These cycles are still valid, but the mAh size are generally sufficient enough to allow the batteries to last at least a couple of years before degrading.
My battery degraded after a year due to not just leaving it on the charger, but having it run a night stand clock all night on a bright setting while it trickle charged.
For devices that don't have a user-replaceable battery, that would be an issue. Not for me. I always get devices that have a replaceable battery.
As far as a battery outlasting how long a person has a device also depends on the person. My wife and I both usually replace a battery at least once, often more before finally replacing a phone. We average about 4 to 5 years usage of a phone before we get a new one, and I used one in particular for 9 years. It's actually still in service as a secondary device right now on it's 5th battery.
While battery tech has gotten better, the very nature of a Lithium Ion battery, which is still used in phones, means it will indeed have cycles to deal with.