Can I leave charging my iPhone all night ? Is that good or bad for the battery

About Optimized Battery Charging on your iPhone - Apple Support

https://support.apple.com/en-ca/guide/iphone/iph63eecc618/ios

Pros:

1. Charge when you want
2. Charge as long as you want
3. You can use while charging
4. You cannot overcharge using Apple supplied cable and charger.
5. iPhone will auto switch OFF when full

Cons:

1. Don't let it run too often under 20%
2. Don't deplete battery at all for no reason