Who would need to press the power button to actually turn off or restart the device, right?
The setting to change this is also pretty much buried under Settings -> Special Features -> Gestures.
(Yes, I have no idea why the Assistant is in German when the phone is set to English either 🫠)
On my S25U you just hold down the down volume button and the power button at the same time. That’s how it came for me stick our of the box, have not touched it. I did set my power button to be one long press for my wallet app instead of Gemini tho