Overwatch 2's approach to new hero releases is much different than the original game. In the first Overwatch, heroes were free forever and immediately available. In Overwatch 2, you have to earn them.
The information out there on how Overwatch 2 hero unlocks will work after the first season is a little incomplete at the moment, but for the three new heroes at launch, it's pretty clear how to get them. If you want to unlock Sojourn and Junker Queen, you don't have to do much for season 1, but new support hero Kiriko has some caveats.
Overwatch 2: How to unlock Sojourn and Junker Queen
To get both heroes for free, non-Overwatch 1 owners have to log into the game before season 2 and Overwatch owners have to log into the game before season 3.
The unlock process gets complicated once season 1 ends on December 5 though. It all depends on if you owned the original game or not.
If you didn't own Overwatch 1, you will only get Sojourn and Junker Queen for free until the end of season 1, which, again, will be on Dec 5.
If you owned Overwatch 1 before June 23, you get an extra season to log in and get the two heroes for free. As long as you get into the game before the end of season 2 in February 2023, you'll be able to redeem the Founder's Pack for them. After that, you're out of luck.
After both periods end, the respective players will have to get Sojourn and Junker Queen through the in-game shop with Overwatch Coins or earn them through hero challenges. Blizzard hasn't specified how many Overwatch Coins they'll be, but I suspect it'll be close to 1,000, or $10 each. The hero challenge unlock path, however is still unknown. Blizzard said the challenges will be "unique" but nothing else.
Overwatch 2: How to unlock Kiriko
Kiriko, the new support hero that can climb walls, throw powerful kunai, and summon a fox spirit to empower her allies, is the first character that's locked behind Overwatch 2's battle pass.
For anyone that owned Overwatch 1 before June 23, you'll get Kiriko for free as part of the Founder's Pack if you log into the game by the end of season 2 in February 2023.
For everyone else, Kiriko will be instantly unlocked if you pay 1,000 Overwatch Coins, or $10, to buy the premium battle pass (you can buy the $40 Watchpoint Pack too). If you opt for the free battle pass, you'll have to play matches and complete daily and weekly challenges. Kiriko is located on tier 55, and in my experience, this should take you a few weeks to complete if you're diligent about finishing your challenges and play in a group for the 20% XP bonus.
In season 2, Kiriko will be available in the in-game store for an unannounced price (probably around 1,000 Overwatch Coins or $10), and she'll also be available as a "unique" hero challenge, according to Blizzard. But as with Sojourn and Junker Queen, it's not clear exactly what that means.
Overwatch 2: How to unlock Overwatch 1 heroes
If you never owned Overwatch 1 and are playing Overwatch 2 on a new account, you'll also have to unlock most of the original game's heroes via the First Time User Experience. New accounts start with a handful of heroes in each of the three roles, but the rest require a bit of a grind.
To get them, it's a simple but long process: you need to complete a maximum of 150 unranked games. The actual number of matches will be fewer than 150 because wins count as two completed games, so expect to play around 100 to fill out the roster.
Blizzard doesn't offer another way to unlock the heroes either through the battle pass or Overwatch Coins. If you want the heroes, you'll have to simply play a lot of the game.