In some laptops it involves a setting in the bios.
It does not always exist.
But the percent of the charging capacity can be set.
Not every battery pack is the same it depends on how many charging cells are in it. Example 8 cells 80% charge. full charge.
10 charge cells 100% charge of the pack.
You can buy batterys with more cells to increase the Whr or running time of a laptop while on battery.
The type of charge also matters, fast charge or slow. Fast charge sometimes does not charge to 100% because it heats the battery faster while charging.
The battery is monitored for heat build up and is also a cut off for the charging cycle.
On the battery pack it should state the amount ofcharging cells contained.
So if it says 8 its 80%