@MO-64 Thank you for reaching out to Microsoft Q&A. Azure API Management supports multi-region deployment only for Gateway component. Management plane and developer portal remain hosted only in the primary region and hence secondary region is not available for you to test. The same has been described in docs: About multi-region deployment.
As mentioned in docs, if the primary region goes offline, the APIM management plane and developer portal become unavailable and the secondary region can serve only API requests.
If you are in need of this feature or would like to share any other feedback, please feel free to share it directly with our product team via aka.ms/apimwish (similar feature: https://feedback.azure.com/d365community/idea/bd2d9096-ff24-ec11-b6e6-000d3a4f0858). This would also help others with similar interests to upvote it. I hope this answers your question and feel free to add a comment if you have any other questions. We would be happy to assist you.
Please 'Accept as answer' and ‘Upvote’ if it helped so that it can help others in the community.