Rocket League offline or single player

My 6yo son wants to play Rocket League, but my 16yo doesn't want him to mess with his online ranking or whatever it's called. It appears the current release of Rocket League doesn't have offline or single-player matches available anymore. Have we missed something somewhere?

How can we let the younger son play rocket league in single-player so that it doesn't affect the older brother's online ranking and matches? It has a training mode, but there don't appear to be any AI players, which I think used to be there previously.

Rocket League, fully updated, on Steam, Windows 10.

Solution 1:

Rocket League is now free on the Epic Games Store. You can create the younger son his own account to play on. He can play online and earn his own rank, without affecting the older son's rank. You can disable chat in the options, if you're worried about that.

If you still don't want him playing online, the single player modes can be found under
Play --> Custom Games --> Exhibition
and
Play --> Custom Games --> Season