App to stop iPhone 12 charging to 100%

App to stop iPhone 12 charging 

I am looking for an application to put on my iPhone that stops the phone charging at let’s say 80%.

I was in the app store, but that is such a jungle, and I cannot find something that works for me.  

Ideally it works completely automatically even if the phone is plugged in for a long time.  My phone hangs often for a day or more on my computer, and so it is always charging.  This is what I want to stop as most info tells me it is not good for the battery.  

Any tips?  

Open source or the likes is also fine with me.