In this example we combine npm workspaces and Typescript project references to "structure your TypeScript programs into smaller pieces"
This is a barebones template, you can simply test it using:
npm run build
npm start
Normally you would use tsc as build script, with project references keep in mind that you need to use tsc --build or tsc -b in order to include references. The composite property in tsconfig, defines the root of your package/module.
Using workspaces unlocks some features that you can benifit from. For example to run scoped scripts npm run test --workspace=backend. You can also scope your packages, for example npm init --scope @app -w ./libs then you can use @app/libs to import for example. Read more on workspaces at workspaces docs