I found a really good solution for me:
1. I installed the app "Mobicip". You have to create an account, so that you can use it on your android phone.
Once installed, you can block all browsers but a new safe browser is provided. You don't even have access to your
phone settings without your account password. Otherwise you could remove the app. Choose a difficult password
and give it to someone you trust.
Nevertheless, I managed to find some nude images with the safe browser. So here comes solution two:
2. Additionally, I installed "AppLock" (Any other app for blocking apps is fine too). With this app I blocked the
safe browser from "mobicip". Again, give the password from this app to someone else.
Now, it is absolutely impossible to watch P or anything else on my phone because there are no browser anymore.
I just use my phone for communication. And if I want to check something on the internet I use a laptop or go to the library etc.