You can create and configure build types in the module-level build.gradle file inside the android {} block.

android { … defaultConfig {…}

buildTypes {
    release {
        minifyEnabled true
        proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
    }

    debug {
        applicationIdSuffix ".debug"
    }
}

}