Line a rimmed baking sheet with parchment paper. In a small bowl, mix together the salt and cinnamon. Set aside.
Heat a large Dutch oven, covered, over medium-high heat for 2 to 3 minutes. Add the coconut oil and heat 30 seconds. To check if the Dutch oven is hot enough, add one or two popcorn kernels to the pan and cover with the lid. Cook until you hear the kernels pop, 1 to 2 minutes.
Add the remaining kernels and the sugar, stir to combine and cover. Shake the pan vigorously to coat the kernels in the sugar and oil. Cook, shaking the pan often, until the popping has slowed to about 2 pops per second, about 2 minutes.
Remove the Dutch oven from the heat and carefully uncover. Pour the mixture onto the prepared pan and sprinkle with the cinnamon salt. Be careful: the popcorn is extremely hot at this point. Allow the kettle corn to cool for 5 minutes before enjoying.