If German chancellor or US president visited Russia, and there were enough desire to arrest them, they would be arrested. I don't see practical means to prevent it.

Similarly, if Putin visit Germany, there's no practical way he may avoid arrest if there's enough desire for it.

We however may argue that there actually will be desire to ignore the international court requirements, as in practice Germany, USA etc. don't really always follow the law. In general we can't say for sure what's going to happen. E.g. escalation is going on since at least February 24th, 2022, so the risk isn't a good argument why this can't happen.