Push Notification - Icon

Hi,

I try to implement push notifications. The basics are fine and also working. Now I try to change the icon etc but this is not working. in the documentation I found the note to change in the app.json under expo>notification>icon the whole thing. But this does not work.

Some other people write in the internet that a specific picture format is needed.

Is there any documentation on this or a tool that automaticaly checks the icon etc?

thx
Stephan