Using Sauté function on Instant Pot, heat butter or olive. Once hot, but not smoking, add in leeks and sauté until the leeks begin caramelizing. Stir occasionally to prevent burning.
Once leeks are caramelized, deglaze using the white wine. Pour wine into Instant Pot and use wooden spoon to stir making sure to get all brown bits off bottom of pot. These are bits of flavor that you want to incorporate into chicken.
Let wine and leeks simmer for a few minutes. Turn off Sauté Function. Add in sun-dried tomatoes, olives, coarsely chopped oregano, thyme sprigs, chicken thighs, and chicken broth. Add in about ½ tsp salt. Gently stir to combine.
Following proper Instant Pot procedure, ensure proper closure of lid. Set Instant Pot for “Pressure Cook” for 18 minutes. When 18 minutes is done, let pressure release naturally for 15 minutes. Then, safely remove lid ensuring all pressure is released.
Remove lid. Set sauté function to and let simmer for 5-10 minutes to reduce slightly. Taste and season with 1-2 tbsp. lemon juice and any additional salt and pepper.