A leak related to Zenless Zone Zero shows an upcoming boss to be introduced during the Version 1.7 update:

• A new variant of the “Ruthless Fiend,” which was first encountered as an Elite enemy.
• This update will also bring two new characters, Hugo and Vivian, and the return of the popular “Grand Marcel Adventure” event.

The latest patch details indicate that HoYoverse will continue expanding the unique combat and challenges within the game, along with introducing new lore elements related to these characters.

For further details, you can visit the official page of Zenless Zone Zero.