Group chat in Teams is one of many ways to communicate with your peers. Teams is increasing the size limitation of this feature to 250 participants.
There is still a limitation on when certain features become unavailable. Some of the features with limitations are:
- Calling (audio and Video) - Max 20 participants: Use meetings for larger groups
- File sharing - Max 10 participants: Use OneDrive, Sharepoint or Channels in Teams for larger groups.
According to the roadmap item 63577, this should be rolling out in May. It is not possible to change any of these settings.