Turn on a multi-cooker (such as Instant Pot(R)) and the select Saute function. Add olive oil to coat the bottom of the pot. Season both sides of the chicken with salt and pepper; place in pot breast side-down. Cook until browned, 5 to 7 minutes. Turn and cook until other side is browned, about 5 minutes more. Turn off Saute function.
Pour milk into the pot with the chicken. Add lemon zest, garlic, sage, salt, and cinnamon. Close and lock the lid. Select high pressure according to manufacturer's instructions; set timer for 25 minutes. Allow 10 to 15 minutes for pressure to build.
Let chicken rest for 5 to 10 minutes. Release pressure carefully using the quick-release method according to manufacturer's instructions, about 5 minutes. Unlock and remove lid. Remove chicken from the sauce; take chicken meat off the bone and cut into bite-size pieces. Place meat back into the sauce; stir to combine.
You can substitute fresh thyme or 1 teaspoon dried sage or thyme for the sage.
If you have a lot of caked-on browning, it could possibly interfere with browning. Rather than cleaning out the pot I would recommend deglazing. To deglaze, take chicken out of the pot and set aside. Add a small amount of milk (or water or chicken stock) to the pot on Saute function. Scrape the browned bits off the bottom of the pot with a wooden spoon. Add more liquid, a small amount at a time until you've released all the browning. Turn off Saute function, add the chicken back to the pot, and proceed normally.