@Joven M. Dativo Thank you for reaching out to us, As I understand you are looking a feature request to limit the users that can be added to an Azure AD Group.
Checked on your requirement, currently we dont have any such feature available within Entra ID Group management to achieve your ask.
Any specific reason why you are looking for this feature ? or you can submit a feature request here - https://feedback.azure.com/d365community/search/?q=group+membership+limit which is monitored by our product team so that your request gets more visibility to our engineering team.
Let me know if you have any further questions, feel free to post back.
Please remember to "Accept Answer" if answer helped, so that others in the community facing similar issues can easily find the solution.