Okay, so there is a possibility of editing sprites allowing people some mods. Here the sprite I replaced after the game is built using UABEA. But you have to replace it one by one which is very time consuming.
You can also have different aspect ratio but you need to do some extra step and for some frame result is not what I expected as you can see some part of sprites is missing in the image below.
I faced this problem before with Emerald's shop where part of it was missing like this. Could be a unity thing or the image itself.
