You can use this technique to keep making a lot of money early on in the game. However, since it is a trick, the developers will likely patch it, and it will eventually cease to function. Anyway, here's how to start Need for Speed Unbound with free, limitless money while it's still active.
Purchase a Body Kit. Pressing left and X on a PS5 or left and A on an Xbox will bring up the body kit menu. Press all of the buttons at once.
Before attempting this cheat, be sure to have your progress saved because it may cause your game to freeze.
After that, select Options, exit the game and then restart. When you choose to continue the story, you should discover that you have extra money to start over. This procedure may be repeated.
As previously indicated, this issue will likely be fixed in the future.