Scott Westover published this tutorial to YouTube is useful for all Phaser developers: "In this quick tutorial, we take a look at how we can split the configuration needed for loading in all of the assets used in our game, from our game code and how we can load this configuration via an external JSON file. By using the built in Phaser 3 Plugin Loader, we can use the pack method to have Phaser 3 dynamically load all of the various assets we need like: spritesheets, images, audio, json, and more!"
How to load assets via JSON
Scott Westover's New YouTube Tutorial: Efficiently Load Game Assets in Phaser 3 Using External JSON Configurations