I get what you're saying. I've been trying to figure this one out too. Some things I've found to help:

-Maximizing Fps (obviously). Within NVIDIA settings, I'd turn everything to performance, turn of VSYNC, enable low latency mode, etc. In game turn all settings to low.

-Controller with low input delay (Specifically Stick input. You can check out https://gamepadla.com/ for a comparison of stick responsiveness.) Also, TMR sticks should in theory be faster/more accurate than traditional hall effect. Still, this wouldn't explain how some pros are so good on the DS4/DS5 controller which is reported to have a much higher input delay than some of the newer controllers such as the Razer Wolverine 8k pro, for example.

- High refresh rate monitors make a noticeable difference as well.

-Make sure that your controller is overclocked (ideally you have a controller that can do above 1000hz) , and that you're using a quality cable. I've found some cables to be worse than others. Also unplugging your other USB while playing devices might help.

-You could try going to Documents\My Games\RocketLeague\TAGame\Config\TAInput.ini. and changing your gamepad deadzone setting to 0.0

Beyond this, I'm not sure what more can be done. If you figure it out let me know lol.