ActiveModelSerializers camelCase transform when don't have serializer class

I found a way to transform object keys from snake_case to camelCase in rails with the ActiveModelSerializers gem

# config/initializers/ams_config.rb ActiveModelSerializers.config.key_transform = :camel_lower

The problem is that for some models I don't create a Serializer class (a class that inherits from ActiveModel::Serializer) but just call in my controller to render json: @some_resource or even render json: {my_key: value}

I want these objects to get transformed to camelCase as well.

How do I make ActiveModelSerializers to be the default serializer which serializes any object I render as :json ?