To use SASS with Angular instead of css, simply add the below parameter to the new command when creating a new project:

ng new [your application name] --style=scss

If you have already created your project and want to switch to SASS, run the below command (having pathed to your application directory:

ng set defaults.styleExt scss

Note that you will need to manually change any existing component css files to the scss extension. When you do this remember to update the 'styleUrls' property in the 'component.ts' file.