Combine water, port, orange juice, sugar, orange zest, cinnamon sticks, and cloves in a multi-functional pressure cooker (such as Instant Pot®). Select Saute function and set timer for 3 minutes, until liquid begins to slightly simmer.
Place pears inside the pot. 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 lid. Transfer pears to a plate to cool, leaving juices in the pot.
Close and lock the lid. Select high pressure according to manufacturer's instructions; set timer for 10 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 lid. Discard cinnamon sticks from the sauce. Place poached pears in bowls and drizzle with port sauce.