Season the Chicken:
In a small bowl, mix together the salt, lemon pepper, paprika, and thyme.
Rub the spice blend evenly over both sides of each chicken breast.

Sear the Chicken in the Instant Pot:
Set the Instant Pot to the Sauté setting. Let it heat for 2–3 minutes.
Add 1 tablespoon olive oil, then place two chicken breasts in the pot.
Sear for about 3 minutes on one side, flip, and cook the other side for 2 minutes.
Remove and repeat with the remaining two breasts using the second tablespoon of olive oil.
Turn off the Sauté function.

Deglaze the Pot:
Pour in the chicken stock and use a wooden spoon to scrape up any browned bits from the bottom of the pot.
Place the trivet into the pot and arrange all four seared chicken breasts on top.

Pressure Cook the Chicken:
Secure the lid and seal the steam release valve.
Select High Pressure and set the timer for 4 minutes.
When done, allow the pressure to naturally release for 4 minutes, then quick release the rest.
Transfer the cooked chicken to a plate and cover loosely with foil.

Make the Lemon-Herb Sauce:
Remove the trivet and turn the pot back to Sauté.
In a small bowl, whisk together 1 tbsp cornstarch with 2 tbsp water.
Stir the mixture into the pot and bring to a boil, whisking frequently.
Simmer for 1 minute until thickened, then stir in the lemon juice.

Serve:
Plate the chicken breasts and drizzle with the warm lemon-herb sauce.