How do I access the planet editor

just get to the settings and search for the console keybinding, so open it and write PlanetStudio

@FaridRjb I think it's possible on android but not ios

It's impossible to use XML on Android. :(

See this post. Be aware that this is still really just a preview of how a planet will work and all editing is done via XML files. This functionality is still in a very nascent/experimental state. Documentation is non-existent as far as I'm aware and what folks have achieved for projects like ESS and RSS is a testament to the authors' industriousness and drive to figure things out by experimentation.

Keep an I out for announcements from the devs here and in future release notes, because a more full featured planet editor is on the roadmap.

Currently editing planets can only be done via XML editing as far as I know.