TL;DR: Naughty Dog has released a free patch for The Last of Us Part II that boosts the game's performance on Sony's PlayStation 5. After installing patch 1.08, simply head to the display options in the game's settings menu and look for a toggle to enable 60 frames per second. It's that simple.
The developer said the new framerate option complements the other performance enhancements that the PS5 brings to the game, including a higher resolution and faster load times.
Digital Foundry was able to get its hands on the patch early, and has been testing (and re-testing) it over the past week. Their results are very promising. In fact, they only came across one sequence in the entire game where there was a dip below 60 frames per second. Otherwise, performance remained buttery smooth at the target framerate.
Digital Foundry's video does include some in-game spoilers, so if you haven't already played through to completion, perhaps you'll want to avoid it for now. Then again, the game has been available for close to a year, so they aren't exactly crossing any moral boundaries here.
The broader takeaway from DF's analysis is that the patch truly is "transformative" in terms of gameplay and improving the overall experience. Things like aiming are now much more responsive and there's a general snappiness to the game, whereas at 30 frames per second, the title had a "moderately heavy feel."