@Denis Pasternak Thanks for posting in our Q&A forum.
After testing, I found that contacts can still be deleted in fully managed devices in kiosk mode, and I didn't find an option to prevent the ability to delete contacts, at least not currently supported by Intune.
And I also searched in Android MDM, currently they do not provide an interface to prevent deletion or modification of contacts, please refer to:
https://developer.android.com/work/managed-profiles
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