So this is all from my experience with UE4 over the years since it came out. I am not an expert. I don’t claim to be an expert. Near enough all of my knowledge is self-taught or hands on experience from my current job so please feel free to take my response to this how you will. All my coding experience with UE4 is only in blueprint so I can’t comment on any C++ questions if you bring them up.
Q: Is it possible to create a 2D point and click adventure game in Unreal Engine 4?
A: Yes it is possible.
Q: How to make the 3D illusion in 2D space for point and click games?
A: This is down to a retro game technique used on the PlayStation 1. You simply create a 3D object but only allow it to
transform on a 2D plane within the engine.
Q: How to make character change in size when moving up / down / left / right / whatever direction you want them to move?
A: This is actually quite simple. If you want the character to shrink / scale down as moving towards the top of the screen for example, take in the screen resolution height and use the map range clamp to change its vale from whatever the height resolution is to 0.5 and 1. Then 0.5 to 1 can be used as a scale reference for the character. When the character is at the bottom of the screen the scale is set to 1 and when at the top, the scale is set to 0.5. I’ve tried to explain that as best I can. You might want to look into the node more though if you are not 100% what I mean.
Q: Do I do this in the 2D Paper view or 3D platform.
A: Something like this, purely point and lick would be done in 2D view but if you wanted a more 3D environment then I would suggest 3D platform but then you’d have to play around a lot more with camera position and scale.