Hello Ankit,
If you are using AdWords API, for example under every field of the campaign entity
here that doesn't support updating mentioned as read only field. It will be same for every other entity in AdWords API. Like wise in Google Ads API also the fields that doesn't support updating having the label read only under the description of each field. Please let me know if you have any specific concerns.
Regards,
Sai Teja, Google Ads API Team

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