Your battery usually does not charge to 100% internally, the system will report 100% but it usually hovers around 96%+ internally.
(You can read more of this here..
https://forum.xda-developers.com/showthread.php?t=871051 this is the best example of how most modern battery does charging now. Which is also why some people see 100% drop off so quickly. Esp on older batteries)
Optimized charging is to keep your battery not too fully charged for prolong duration which is also a reason that accelerate wearing out the battery. Phones already do it internally just optimized charging puts it at a lower value for a longer duration and only brings it back up to full just nice or slightly before you usually pick up your device.
So it should look like this for optimized charging on your battery graph.
And with a notification like this.