Splatoon 3 was shown off in more detail yesterday during its very own Nintendo Direct. Here it was announced that if you have Splatoon 2 save data, you'll get a whole bunch of in-game bonuses.
"If you have save data on your system from the Splatoon 2 game, you'll get some neat-o bonuses to help you hit the turf running," the Save Data Bonus description reads. The first reward listed is three Gold Sheldon Licenses which can be given to Sheldon to receive "your favorite weapon types more quickly, regardless of player level."
You'll also be able to join Anarchy Battles right off the bat without needing to worry about level. As for ranks, your time in Splatoon 2 wasn't for nothing as you'll start with a higher rank based on the one you earned in the previous game. This also means that you'll "get matched against players who achieved a similar skill level to you in Splatoon 2", meaning that you'll essentially pick up where you left off.
However, if you want to start fresh with ranking and skill level, you can always delete your Splatoon 2 save data before you boot up 3. The downside to that though is that you'll lose out on the Gold Sheldon Licenses, but Anarchy Battles are something you can earn simply by levelling up.
For players new to Splatoon, this means you're less likely to get paired with more experienced players who have dabbled in Splatoon 2. It's more likely you'll be paired with other fresh faces, giving you a fairer fighting chance.
It was also revealed that Splatoon 3 is getting a story mode that serves as an "epic finale" to the saga, and it even features a turf war-inspired card game. During the Direct, we also found out that Splatoon 3 will have 12 stages on launch and Splatanas, new ink swords, while all previous weapons are returning. So you can get stuck in with something familiar and even get a head start as a reward for playing the second game.