I have a 2 years old SER5 (with 5600H) and even on this model (2x HDMI) I was able to connect a monitor on the front USB-C to have 3 screens, so it should work for yours too.
Thank you very much for this answer. I thought already in that way. But I would it find better using the rear outputs, because of a disturbing USB-C connector in the front. Maybe is there an other choice?