In older games like this, input handling isn?t always perfectly linear, so even if everything seems fine in settings, the actual values might not be hitting their maximum.

You might want to check:

In-game or system calibration
Deadzone settings (too high can limit range)
Whether the input is being mapped correctly (especially if using any wrapper or emulator)

Before changing too many settings, it?s worth verifying the controller itself is outputting correctly. A lot of times it turns out to be hardware-related (wear, drift, or limited range).

You can quickly test it here:
https://devicexa.com/tools/gamepad-tester/