Pour beer into a multi-functional pressure cooker (such as Instant Pot). Stir in shrimp, butter, and seafood seasoning. Close and lock the lid. Select high pressure according to manufacturer's instructions; set timer for 2 minutes. Allow 10 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. Stir in parsley.
Transfer shrimp to serving plates and serve with cocktail sauce for dipping.