Can i charge iphone11 overnight

Yes you can, make sure you have below option enabled. With iOS 13 and later, your iPhone learns from your daily charging habits to improve the lifespan of your battery.

Settings > Battery > Battery Health > Optimized Battery Charging.

Here are detailed about this option:

https://support.apple.com/en-us/HT210512

Yes, you can charge it overnight. It will not overcharge.