build.gradle

apply plugin: "com.android.application"
// Add the following
if (isNewArchitectureEnabled()) {
    apply plugin: "com.facebook.react"
}

android {
  // everything else
  if (isNewArchitectureEnabled()) {
    // everything else 
    
    // Add the following
    packagingOptions {
       pickFirst '**/libhermes.so'
       pickFirst '**/libjsc.so'
    }
  }
}

// At the bottom
if (isNewArchitectureEnabled()) {
    react {
        libraryName = "CustomModules" // tells about the name for your library to use when generating artifacts for ini
        codegenJavaPackageName = "com.rearchdemo.custommodules" // A string that represents the Java package your code should use
        root = rootProject.file("..") // path of your root project
        jsRootDir = rootProject.file("../src/custom-modules/specs/") // path to your Spec folder
        reactNativeDir = rootProject.file("../node_modules/react-native/") //  Reference to the react-native package root
        codegenDir = rootProject.file("../node_modules/react-native-codegen/") // Reference to the react-native-codegen
    }
}