IPhone Battery charge cycle

A charge cycle is ANY combination of discharge/charge combinations that total 100%. If you use 20% of the battery each time and recharge it 5 times, that will be one charge cycle.

There is absolutely no requirement to tey and micro-manage the charging process.

You can charge at any time, for any amount of time.

With any lithium battery it is best to try to avoid frequent or regular deep discharge cycles. Certainly it is not good to always run them down to the point the device auto-shuts off. Those very deep cycles degrade a lithium cell faster than shallow(er) cycles and more frequent charging (full or partial charges, as convenient to do so).

With the slow trickle charging at the end of a charging cycle, and with charging cutoff when at capacity, there’s no reason to worry about the full charge end of things. So regularly charging to 100% is fine.

For iCloud backups the simplest thing is to leave the device plugged in overnight, and all charging stops once the battery is at capacity.