This seems kind of like two separate requests:
- An Automations Trigger that executes if/when Battery Cam Pro determines that external power is lost. (An Action “that can…manually be triggered” would just be a Shortcut Automation.)
- An Automations Action that can switch microSD card recording mode.
The second is an existing request in this Wishlist topic:
The first I haven’t seen specifically requested elsewhere but probably belongs in this related topic:
One of the requests in that second topic seems like it’s headed in that direction or at least adjacent:
If you haven’t already done so, you can visit those topics, click or tap the Vote button above the initial post, and share your ideas and use cases in the comments.