From mid September '21, meeting organisers of both channel and private meetings will be able to create breakout rooms ahead of the scheduled meeting start.

Meeting organisers will be able to access a new tab in the meeting's calendar item labelled 'Breakout rooms'. that will enable them to pre-create breakout rooms and pre-assign participants.

Organisers will be able to: 

-Create rooms (individually or in bulk) and delete rooms

-Rename rooms

-Assign invited attendees to rooms

-Configuring meeting options for each room

-Adjust breakout rooms session settings such as timer, assign breakout rooms managers and more)

Unfortunately, from the information released by Microsoft, the update doesn't seem to include being able to enter into the rooms to set them up with activities. I live in hope.