We don’t know yet, but Season 3 Heroes are currently in Beta.
You can read more about that here: 🧪 Early Information on Season 3 Heroes [Part of The Beta Beat V26 & V27]
We don’t have an official answer about this at the moment, but considering you can’t even get Season 2 Heroes from Training Camps yet, it’s extraordinarily unlikely that will happen anytime soon for Season 3 Heroes.