Patches for Cities Skylines 2 are in the works, and in the meantime, the developers are introducing the map creation tool. They are adopting a new approach: now a single editor combines multiple functions (rather than several separate dedicated applications).
With the Cities Skylines 2 editor, you can easily create a map, configure the terrain, climate, and even create your own assets and apply them in the future.
This Cities Skylines 2 editor is currently in beta. It is not specified when it might be released / made available to regular players.
Video: https://youtu.be/a7ecXBwRhdQ