Question about Steffen Wireless adapter plug with remote control

YES - Status light is also a switch

yes you can - it has a red light and you can press it

Yes (switch on/off manually). This is the small button at the top of the socket (see photo). It is also used to initialise the connection with one of the 3 on/off buttons on the remote control.

The statement by bruno2166 is wrong.

Yes, it has a button with illumination.

Yes.

Yes

So I can interrupt the power to the device connected to the plug?

I now have a multiple plug with such an on/off button and I would love it if this plug also had this and not just via remote control

no

Hello BigDan86
No, the control is only possible via the remote control.