@SJ31 , Based on my research, we can set Edge as the default browser by setting "com.microsoft.intune.useEdge" as true. Here is an article for the reference:
https://eskonr.com/2019/03/how-to-make-edge-browser-as-default-browser-on-mobile-os-for-managed-apps/
Note: Non-Microsoft link, just for the reference.
Hope it can help.
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