Thanks for joining us here in the QuickBooks Community, danuj.
We have a separate Community site specially created for API questions and developers like you.
Please visit this link so our developer support and other API users can help with your question about adding company timezone using your app: https://help.developer.intuit.com/s/.
You can go directly to the Questions tab, then click Ask A Question.
Please let me know or visit us again if you have other questions regarding QuickBooks Online. See you around.