A free mod for Red Dead Redemption 2, by Schckrabby.

Proper Horse Sprint on Controller is a simple, fast, and fun way to get rid of the annoying speed limits in-game. It allows you to sprint at any time and skip over any obstacle without having to tap the button every time. This is perfect for gameplay where you need to rush to the finish line without getting hit by an obstacle. 

In order to use it, you need to install the script hook RDR2, which is an add-on for the game. The way it works is that it allows you to use the gamepad for the race. The way it is implemented is that it is used to sprint the horse and is not used for anything else.