Are there audio interfaces where you can switch the audio output?

I produce music on the laptop (Fl Studio) and sometimes record something live, and I lack the function that before I play something and you can hear it on the monitors, I might just play a few sounds or something from the headphones, so that I basically have a toggle function. I could imagine that there's such a thing with audio interfaces, but I hardly know anything about it, can my idea be implemented?

A mixer with 2 outputs (if your headset doesn't work with usb).

So audio interfaces don't offer this feature?

You need a controller and channels, I don't know any

Okay, could you maybe send me an inexpensive example?

There are many but look ma at Thomann

There are some where you can completely route and control the headphones and other outputs as you like. From RME for example.

Most interfaces don't have such a function, and I don't quite understand what it should be for? When producing, you use headphones and monitors (actually it is best to use monitors) to hear whether everything fits, sounds good, etc., so what an extra "preview function" for the headphones, if you do this with the monitors too can?

As I said, it's about playing live, that means I support a live-playing band with electronic sounds. And what about these "Phones" controls, which you often see on interfaces, do not control the volume separately for the connected headphones?

Yes, most headphone outputs can be controlled. It comes out exactly the same as with the monitors, so simply turn the monitors down and listen to headphones is no problem.