If I use any of the cheats will it prevent me from being able to unlock any of the trophies in the game?
Most of the time this is true, but strangely enough, you can use cheats in Grand Theft Auto 3 and it does not stop trophies from being unlocked.
This means you can spawn a rhino if you are having a hard time with a car mission, give yourself guns or health during a tough mission and it will not block any of the game’s trophies.
This has been tested several times. I was personally able to perform the money cheat and I got the trophy for getting $1 million.
Cheats can have an effect on your total criminal rating, so use them sparingly if you have yet to get this trophy and intend on going for the platinum.