Google Duo, along with any other video chat app, is developing at an accelerated pace. In the past month, Duo has increased the group chat limit to 1
After sending his new promotional email, which also promotes Duo's end-to-end encryption and AR video effects, Google confirmed Duo chats for 32 people with Android Police. Google first hinted at a higher video chat limit in March but still has not announced exactly when the 32-person limit will take effect.
Google Duo is a casual video chat tool for families and friends, but the limit of 32 people will certainly open the service to some small businesses and teams. If you need a larger chat limit, you should use Google Meet, a conference tool that allows up to 250 participants to participate. Google Meet is usually offered as part of G Suite, but is currently available for free to help people communicate during the pandemic.
Source: Google via Android Police