I\'m entirely unfamiliar with Unity3D\'s more complex feature set and am curious if it has the capability to take a picture and then manipulate it. Specifically my desire is
If you want to do that without using a third party plugin then @FuntionR solution will help you. But, if you want to save the captured photo to the gallery (Android & iOS)then it's not possible within unity, you have to write native code to transfer photo to gallery and then call it from unity.
Here is a summarise blog which will guide you to achieve your goal. http://unitydevelopers.blogspot.com/2018/07/pick-image-from-gallery-in-unity3d.html
Edit: Note that, the above thread describes image picking from the gallery, but the same process will be for saving the image to the gallery.