An extremely comprehensive, well written and illustrated tutorial on tilemaps in Phaser 3, written but the developer who built the tilemap API.
Michael Hadley has written a superb tutorial on creating modular game worlds in Phaser 3. The first part of the tutorial deals with the use of Static Tilemaps. It goes from a blank file to creating a full Pokemon-style top-down game world that a player can explore.
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.
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 CodePen examples as well. This is a masterclass in both tutorial writing and the use of tilemaps, so I'd urge anyone who plans to use them to read it.