Here's a tool you're not likely to find in the average DIY'ers toolbox, but which electrical contractors will have in their truck: The knock-out punch tool (also called a slug-out driver or a knock-out driver). Below is an example by Panasonic, which features an articulated head in case you need to come in at an angle:

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Power tool company Milwaukee's designers eschewed the articulated head, but sought to improve this sort of tool in another way. After closely observing the ways in which contractors actually use them, they developed the following "quick connect" innovation for their Force Logic Knockout Tool:

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Lastly, if you just need to knock out a couple of holes and don't want to invest in a dedicated power tool, there are wrench-driven variants like this Klein Knockout Punch Set (though you still need a drill to make the pilot hole):

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