Horizon 4 X Box one Multiplayer

Morning Guys
Can someone help me please - i got my son the X Box One Forza Horizon 4 for Christmas and bought a second controller so we could play against each other, but it seems that this is not an option? Can we play against each other offline or do i need to buy a whole new console and make a profile in order to race each other?
Please help - thanks.

first. merry christmas!!
i think that you need to buy another Xbox to Play Multiplayer with you son.
There are some games that you can play multiscreen but Forza Horizon 4 not support this option.
if i can help you im here.