Whisk chicken broth, soy sauce, honey, garlic, red pepper flakes, and pepper together in a multi-functional pressure cooker (such as Instant Pot). Add chicken thighs and turn to coat with sauce. Close and lock the lid. Select high pressure according to manufacturer’s instructions; set timer for 8 minutes. Allow 10 to 15 minutes for pressure to build.

Release pressure carefully using the quick-release method according to manufacturer’s instructions, about 5 minutes. Unlock and remove the lid. Transfer chicken thighs to a plate and keep warm.

Select Sauté function. Stir together water and cornstarch in a small bowl; add to the pot. Cook and stir until sauce has thickened and reduced, about 5 minutes.

Return chicken thighs to the pot and toss to coat in hot sauce.