If you use Zoom with AssistiveTouch, you can change how the zoomed in area responds to the pointer location, just go to Settings > Accessibility > Zoom, then select Zoom Pan. You'll have these options once you enable Zoom Pan: If you click again, it will release the drag locked item. This will allow you to hold the input key until the item is ready for dragging, then move it to another location without continuing to hold the button.
To configure the ability to drag items without holding a button on the input device, enable the Drag Lock function.