We're just a few days away from trying out Sonic Racing: Crossworlds thanks to the Open Network Test that's happening between August 29 and September 1. Exactly what the test will include hasn't been confirmed yet, but Sega has at least stated that there will be crossplay.
They posted this on social media:
"You can enjoy cross-play on supported platforms during the Open Network Test. Invite your friends and join the fun!"
By playing the Sonic Racing: Crossworlds test, you will be rewarded with "exclusive decals and an in-game title after launch". If you would like to participate, you are free to do so without any requirements, but for Switch 2 you need an online subscription.
<social>https://x.com/RaceCrossWorlds/status/1959284505082056726</social>