Can I obtain Microsoft OEM .XAP .APPX files? where to start?

I need to obtain the APPX files (APPX and XAP would be better) for apps pre-installed on windows phone 10 , (8.1 & 10 would be better).
The usual stuff calculator, camera etc etc

I have access to numerous models, Is it possible to copy them from the device or obtain them from elsewhere?

I have scoured MS website's with no luck.
Any pointers would be gratefully received !

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