Michael Hadley has been writing a series of tutorials on using tilemaps in Phaser 3. In the first part he covered static maps and creating a Pokemon-style game. In this, the second installment, he dives into dynamic tilemaps, where you can manipulate the map data on the fly. He uses this to create a puzzle-y platformer where you can draw the platforms to help the player get around obstacles.
Michael was the developer responsible for coding most of the tilemap API inside of Phaser 3, so you can be sure this is a detailed and well researched tutorial, not just another 'export your map from Tiled' affair.
As with the first one, the tutorial is extremely well written, with plenty of great illustrations and explanations of the concepts behind tilemaps and how they work in Phaser. As you'd expect, the code is all available in GitHub too, and there are copious embedded examples. This is another masterclass in both tutorial writing and the use of tilemaps, so I'd urge anyone who plans to use them to read it.