No, but it will take a few charge cycles to get an accurate reading. iPhone will re-learn what 100% is, based on how the battery behaves. It is recommended that your run your phone for a couple of COMPLETE charge cycles:

1. Charge it to 100%.

2. Leave on charger for an additional hour.

3. Don’t charge your phone again until it is below 5% (ideally, until empty).

4. Repeat once.

This gets you back to accurate reading, sooner. More importantly, it’ll extend the life of the battery.

Also do this if you haven’t used your phone in a while (a couple of months or more).

Read more about this by looking up: priming a lithium battery.

Last note: do not leave a lithium powered device on its charger all day or 24/7. (Laptops, phones,etc.). It’s bad for the battery and will greatly reduce its life.

This is why, when you charge your iPhone overnight, on a regular basis: iPhone will charge to 80%, then finish the charge in the morning. Batteries degrade/deteriorate faster at 100%.