How to check if a custom field exists in Jira using forge app?

I am writing a plugin to read/update existing custom field in Jira. As most agile implementation of Jira has acceptance criteria custom field setup, I am trying to check if the custom field “Acceptance criteria” exists and read/write to the field. However this field is not created by my Forge App.
Anyway to make this happen. ?

Hello @SushilBhattachan

You will have to rely on the Jira REST API.
For example, you can use Get fields to check for the existence of the field.
You will have then to check the Screen and ScreenScheme to make sure your field is displayed in the Jira view.

Thanks for your response. And my goal is to read and write to the customer fields created by Admin.
However following article says a Forge plugin can only update value of the custom field it created. However what about custom fields created by admin, can a forge api update it?
Trying to use API Update custom field value
Highly appreciate your response.