Oh no you are one of them people. Slow charging isn’t going to preserve your battery health by any substantial amount. Fast charging isn’t going to kill your battery by any substantial amount.
Just use your phone and stop being worried about useless crap like that.
You clearly aren’t you admitted you don’t let it go above 80% as if we are in some archaic ages again.
I decided to check if Zenphone had a similar thing to apples smart charging and it does. You can set it to steady charge and rather than “smart” charging where it learns your typical sleeping times it has schedule charge so it only hits 100% for you waking up.