A battery isn’t like a fuel…
A battery isn’t like a fuel tank, where full and empty are hard limits. The 0% and 100% charge levels are basically where the operation is safe and won’t significantly degrade the battery.
When charging, the systems will stop at the designated 100% level. It’s physically possible to put more charge into the battery, but it’s not good for it, and the charging system won’t let you.
Similarly, when discharging to the 0% level, it’s still possible to pull more energy out. In some cars, the designers will let you, since it’s likely better to allow it on rare occasions than to leave you stranded. But you shouldn’t plan on making use of this extra margin.
Most gas cars will display empty with 0 miles of range, when there is maybe half a gallon or so in the tank.