Hi @Watri_Wahab and welcome in the MongoDB Community 
!
I’m not sure which TZ you are talking about.
Each Atlas project have a custom TZ that you can modify here:
But if you are talking about the TZ in the actual ISODate values that you are storing in your cluster, it depends on the back-end code that is generating these dates. MongoDB doesn’t interfere with the data that is being stored. Send X => Store X.
The TZ in the Project Settings doesn’t affect any of the data. It’s just for the metrics, alerts, windows maintenance, etc.
That being said, MongoDB can transform the ISODate you stored and present them in the TZ of your choice.
If I remember correctly, all these operations support an optional timezone field.
Cheers,
Maxime.