1👍
In traditional object oriented development, you’d first solve your problems by designing the shape of your classes. When it comes to storing objects in a persistant way in traditional RDBMs, you’d use some ORM techniques to "flatten" the object internal data into tables. This may be done for example by crafting an ERD model (or some implementation level UML class-diagram). The ERD could then be used to generate the db.
With django, it starts likewise: you’d first design your django views and your django models with classes. Django takes care behind the scene of the tables and columns/fields, so int reality you don’t need an ERD. Now if you want to use the database also outside django, you’d need to provide an overview of its structure. And this is where the ERD comes into play.
Note that django being class-based, you could as well use an UML model instead of an ERD. This has the advantage that you could also document the methods of each class directly in the schema.