If there’s save data from Splatoon 2 on your Switch, part of it can be transferred to Splatoon 3, and transferring the data will net you three Gold Sheldon Licenses that you can exchange for main weapons, regardless of player level.
Did you know that save data from Splatoon 2 can be transferred to Splatoon 3?
You can transfer save data once per Nintendo Account by launching Splatoon 3 or entering the lobby while connected to the internet.
And there’s even better news: according to the official Splatoon 3 website, you will also receive save data bonuses.