Hi @ParimalPatil,
Do you want to open Primary camera of your device in fullscreen mode when using Camera control?
If you want to open Primary camera of your device in fullscreen mode when using Camera control, I afraid that there is no way to achieve your needs in PowerApps currently.
As an alternative solution, you could consider take a try to make your Camera's Height and Width fit your PowerApps app's screen. I have made a test on my side, please take a try with the following workaround:
Set the Height property of the Camera control to following:
Parent.Height
Set the Width property of the Camera control to following:
Parent.Width
In addition, I also agree with @gautmish's thought almost. You could consider take a try to add a Add Picture control within your app instead of Camera control.
When you click the "Add picture" control within your app, it would prompt you that how to choose a photo file. You would have three options -- Take Photo, Photo Libray and Browse:
You could choose "Take Photo" option as above to choose/capture a photo using the nature Camera of your device.
Best regards,
Kris