i am learning about X2 checking examples, but all load some tilemap.json ...
is the only way to create maps for X2 is using tilemap? can't it be manually?
You can do everything programmatically. X2TileMap reads the information from the Tiled json and calls the same API that you can call.
Many of the examples only use Tiled to define the objects. This is recommended as it will save you a lot of time.