First of all make sure your lamp is configured properly in Thinka (see KNX) as a lightbulb. Then you can just say: “Hey Siri, set the floor light to 50 percent”, “Hey Siri, decrease the floor light by 25 percent” or “Hey Siri, dim the floor light”.
In case something is not clear or not working according to your expectation you can contact us, and we will provide instant feedback. We can be reached by email at support@thinka.eu, or by phone at +31-20-2420666