I have an image that I took at an angle, so it isn't a perfect rectangle:
How would I pull the bottom left and bottom right corners in so that they line up perfectly with the top two corners?
I have both Photoshop and Sketch.
You can use a Perspective Crop tool in Photoshop: https://helpx.adobe.com/photoshop/using/crop-straighten-photos.html#transform_perspective_while_cropping
If you do not have Photoshop, the app Office Lens will do this.
You can either use it to take the photo directly, or load in a photo from your camera roll (the latter is the method you want).
Open the app and tap the gallery icon
Select your photo. It will try to auto-fit. This can be very accurate. For my image, it was not. Tap the Edit Points button:
Drag the points to where you want them, and then tap done:
The finished image:
The app is also available for iPad (and Android) which provides a somewhat easier editing experience.