You can connect your iPad to your iPhone using Detail iOS and Detail iPadOS to use your iPad as a monitor to see yourself while recording in Detail iOS using the rear camera.
Step 1. Set up your devices
Place your iPhone on a tripod with the back camera facing you
Place your iPad on a stand with the screen facing you so that you will be able to see what the iPhone camera is showing
Step 2. Start a new project on both devices
Open the Detail app on both devices
Start a new project on both devices