It runs perfectly; fixed 60 fps and it never dips. You can purchase the levels of Hitman 2016 and 2 as DLC on PSN.
Hitman 2016. Though for the reasons that I have mentioned, you should really buy the levels of 2016 as DLC for Hitman 3, so you can enjoy all the benefits of Hitman 3's better UI, controls and graphics.
Hitman 2016 DLC for Hitman 3: https://store.playstation.com/fr-ca/product/UP4572-PPSA01768_00-S1GOTYH30000DIGI
Hitman 2 DLC for Hitman 3: https://store.playstation.com/fr-ca/product/UP4572-PPSA01768_00-S2GOLD000000DIGI
Damn. That seems like the best way to jump in but it's over £100. I feel like they should release a Hitman 3 bundle which includes the prior two games, rather than making folks buy the game and then the DLC. It makes the decision harder. I'd probably jump in if the whole thing was £99.99 or something.
Maybe I'll wait for a sale.