Whisk together the flour, oats, cinnamon, coconut, pecans, baking powder, and baking soda in a large bowl; set aside. In the bowl of a stand mixer fitted with the paddle attachment, cream together the butter, light brown sugar, and salt until creamy, about 4 minutes. Add in the egg and vanilla extract and mix until fully combined.
Add the flour mixture and continue mixing until just combined; make sure to scrape down the sides of the bowl as needed. Cover the cookie dough tightly with plastic wrap and refrigerate for 1 hour.
Preheat the oven to 375° F. Line two large baking sheets with parchment paper; set aside. Once the dough is chilled, remove it from the refrigerator.
Next, scoop out 1.5 tablespoons of cookie dough balls and drop them onto the prepared baking sheets; make sure to leave a little room between each cookie dough ball as they will spread a little while they bake.
Bake in separate batches for 10 to 12 minutes or until the edges are lightly golden brown and the top is set. Remove from the oven and cool on the baking sheet for 5 minutes, then transfer the Oatmeal Cookies with Coconut to a wire rack to finish cooling.