Create ionic 4 app inside Angular CLI projects structure

So there isn't an official ionic cli command that can do this, but you can do

ng add @ionic/angular

In the Project and it will add the necessary pieces to the web app for you.

Other than that, there's always the manual way of installing ionic/angular

• npm install @ionic/angular
• npm install @ionic/angular-toolkit
• add the styles listed here in your styles array
• include the ionicons assets listed here
• add the native build tasks listed here. This is optional if you're planning on deploying to native iOS and native android