This post goes over how to resize or scale an image in Ren’Py using a transform statement.
Half Size
Transform to make an image 50% smaller:
transform halfsize():
zoom 0.5
Use in game/script.rpy:
show eileen at halfsize, center
Transform
Transform to resize an image:
transform scale(ratio):
zoom ratio
Use in game/script.rpy:
show eileen at scale(0.5), center