Broadcast intent action notification for dark mode

I’m trying to toggle dark mode on my phone because there’s no way to schedule this on my device, and so far I have this:

service: notify.mobile_app_phone
  message: command_broadcast_intent
    intent_extras: themeName:Dark

However I’m getting no reaction from my phone. I’ve tried variations on the above but gotten nowhere, where am I going wrong?

My phone is a Huawei P30 running EMUI 12, and I’ve granted the home assistant companion app permission to write system settings.

these actions are generally only reserved for system apps, if you check the companion app logs you will see a failure for missing permission and that permission is only granted to system apps.