Nice to see you again here!
It depends on which OS you are using.
If it’s Andriod, please have a look at here: Import .kml/.kmz file (Android) - PIX4Dcapture
If it’s iOS I recommend going through this thread, How to import an area of interest polygon in the Pix4DCapture app IOS version?
The feature is not there for iOS version. Feel free to provide your suggestion on why it would be useful in iOS version in this thread!
Sincerely,
Rosana