Use a 4 point plane or a grid to transform an image. This modifier is more or less the equivalent to the Perspective Remapping
for it's basic manipulations, but is far more versatile and can help you a lot for mapping purposes.
Here is a quick tutorial:
Select the modifier and go in edit mode, you can now place the point that will define the border of the zone you are going to transform.
Now you can uncheck the Edit Source inside modifier's parameters.
And finally distort the image.
If you want to transform the whole image in perspective, better to use the Perspective
of the 2D Renderer
If your aim was to use a mesh warp, the go check for the Bezier Patch
Create a custom grid warp
New points can be created inside the Warp modifier through the edit mode by CTRL+click on the Viewport
Then by un-checking the "edit source option" you can use them to distort your image.
Note that a split view can be used through the use of the visualizer arrow (next to the modifier inside the Element Tree
) in order to edit the IN and OUT points of the warp deformer at the same time: