Hi,
You can write a script to check the number of profiles in your subscription and check if it reaches the limit periodically. But there is no alerts on checking the quota that I am aware of.
You can use this command "Get-AzTrafficManagerProfile" and put it in a variable and count the profiles in a specific subscription. Then when you have the number, just compare it with >190 and trigger an email.
Regards,
Msrini