Switch controlled by open/closed circuit

You describe a switch which outputs 12V. That is the first diagram.
However that is very simple so I then assumed you need a switch in one place which gives 12V somewhere further away. That is the second diagram.

For the 12V supply you need a battery or a 12V brick (One of these black boxes which plug into the wall). You have not specified how much current you need to switch. What is connected to the 12V?

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From your comment: you want the remote point to switch off when the switch is pressed. The simplest way is to use a different type of relay. This way the relay only takes power as long as you press the switch.

^{simulate this circuit – Schematic created using CircuitLab}