I'm on the 12 Mini without any care with charging, it's at 89% capacity. I do have "Optimised Battery Charging On" apparently, not sure when that was added? Might've always been on not sure. From the description:
"To reduce battery ageing, iPhone learns from your daily charging routine so it can wait to finish charging past 80% until you need to use it."
So I imagine it stops charging or fast charging after 80%. And slow charges that last 20% for when it expects you to need the phone. Not sure how much this differs from only ever charging up to 80%.
I also use Carplay wired, so it's always charging in the car as well.
Just checked my iPhone 11 (work phone) it's at 86%, that's the normal sized model.