I’m just wondering if unused assets (e.g. models, materials, textures)—that is, they’re not in the scene, just the asset library—are downloaded when a user play’s a project? Or do only used assets get downloaded?
All assets are downloaded unless you set preload to false for each asset. You can set preload to false and load the assets dynamically in your scripts or they will automatically be downloaded if an enabled component references them.
Is it correct that if no enabled component references them (i.e. they’re used nowhere), they’ll still be downloaded?
Yes they should be downloaded. If you don’t want them to be downloaded setup preload to false.