@JC 1234, Thanks for posting in Q&A. Based on my experience, there's no setting to keep the default app when doing corporate owned fully managed device enrollment.
You can check if the app can be added via Managed Google Play store app or Android Enterprise system app.
https://learn.microsoft.com/en-us/mem/intune/apps/apps-add-android-for-work
https://learn.microsoft.com/en-us/mem/intune/apps/apps-ae-system
Hope the above information.
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