Cool. Yep they are prequelz to SOTL and Hannibal.

The Hannibal TV series is also starts off as a prequel to Red Dragon and works it's way into Red Dragon, while also barrowing elements and stories from the other novels, as season 3 in particular takes the Florence plot of the Hannibal novel/film and mixes it up with some Hannibal Rising elements, but the second half of season 3 plays out the Red Dragon story line.