How to enable optimizejs minifyjs etc

I see that ionic cordova build android --prod --release doesn’t trigger the minify, optimise flags

How do I make sure all possible optimisations are done before the app is built.

build output:
ionic:lib:build aot: false,

ionic:lib:build minifyjs: false,

ionic:lib:build minifycss: false,

ionic:lib:build optimizejs: false,