Welcome to the forum @nickdoesrobotics !
In this case, it may be helpful to include your code, so that way we can figure out exactly what changes you could make.
Are you hoping to do this for the drive or a different part of the robot?
For the drive, one suggestion I have could be to multiply the joystick value by 0.5 to reduce it by half. This does have an unfortunate drawback that you can’t really go at full speed during driver control. To solve this, you could program a button on the controller so that when it is pressed, the drive only runs at half speed, and when it is not pressed it runs at full speed (or vice versa if you felt like it)
Another suggestion is you could try and use an exponential drive function. I’m not really sure that this would help you very much:
For using the buttons to control motors, you can likely just change the speeds.