Hi @IT Support
Group chats in Teams can accommodate up to 250 users, which is by design. In order to expand the maximum number of people in the group chat, you can send a feedback directly to Microsoft Feedback to add it in future updates.
Many features of our current products are designed and upgraded based on customers’ feedback. With requirements like this increase, the problem may well be released in the future.
Also, based on your description, I think creating a Team is a good option when you need to chat with more than 250 users. Teams can accommodate up to 10,000 users, and you can chat in the team's channel.
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