No you don't need to clip their nails.
If their nails do get too long or sharp you can put a brick in their cage to help wear them down, or use lava ledges.
If they really do need clipping maybe use the clippers meant for cats? I used those for a guinea pig... But rat nails are smaller... Or file them with a nail file, maybe.
But I doubt you'd ever have need to manually clip their nails, they keep them short by themselves just fine.
I decided to make a rock garden in their litterbox instead of use litter. I just bought a bag of river rocks from the dollar store, washed them and put them in with aspen. Walking across it can help keep down the nails. Also, lava rocks and lava ledges are amazing. Also try pumice stones. They are made for chewing, but mine don't like to chew pumice. They do love to chew on the lava rocks, though. You could also try to get an emery board toy that is made for cats (no catnip toys, the dose would be too high for a rat). They would probably enjoy climbing on it during playtime. All of these can help keep their nails trim! I used to trim their nails with baby nail clippers, but I had to stop. They're a lot bigger now and it's hard to handle them without risking an accident. I would definitely try safer alternatives, like rocks.