While I am expecting more PC ports than just Horizon, that could mainly be referring to MLB The Show. Starting with MLB The Show 21, the series is going multiplat, will be releasing on Xbox and Switch as well. Rumor is that MLB got sick of losing out on money due to Sony exclusivity, so they threatened to pull the license and sell it to EA or 2K if Sony didn't go multiplat. That's not confirmed of course, Sony may have decided to make the series multiplat of their own volition, but I doubt it.
To be clear, the studio that makes MLB will pull a Mojang and deliberately make games multiplat? Color me surprised I never thought Sony would ever do that.