I had a doubt whether a toggle can trigger a pop-up screen/modal? But it's not a confirmation modal/pop-up screen.
For example: Turning the toggle to ON state will open up settings modal.
Technically it could, but it's not the expected behavior. When clicking on a toggle the user expects to switch from a state to another , he does not expect to get a pop-in. Except if it's an important warning really related to the state on wich the user have just switch on by clicking on the toggle , i would personally not recomend to use a toggle to trigger a pop-in... just my 2 cents
If it is not a confirmation pop/up (which you should try to avoid, since users tend to get them out of the way without reading the message within) the answer is no.
I have to say that I'm thinking about a switch as toggle. A switch does enable or disable something full stop. I doubt that a user would expect something else using a switch. If it triggers a modal screen, the switch would be no longer accessible. Therefore the user would have to find a way to get rid of the modal in order to switch off the option. This would be weird. Without having a more concrete context(what is the problem you are trying to solve) it is difficult to give an advise or examples of other solutions. Something that crosses my mind is instead of showing a modal just show or hide something below the switch. This would work with the mental model of a switch.
I agree it's not expected behavior and in the example given which is to expose the Settings option, why not just have the user click on the Settings icon or button? A toggle or switch is to toggle/switch between two binary values so it's not to be used for opening modals because in the example given, it would mean the value is Settings Window Open/Settings Window Closed.
When choosing what function the toggle should perform, remember that this control is a metaphor taken from physical interfaces: the lights switch, the Silent mode toggle on a fan... So the function should be a binary one because it's a toggle between on and off modes e.g. [Toggle On/Off] Apply Rules.
The toggle is a relatively new control and previously, interfaces used either a single checkbox or two radio buttons.