ImageTextureLayered | Godot Docs 4.4

# Fill in an array of Images with different colors.
var images = []
const LAYERS = 6
for i in LAYERS:
    var image = Image.create_empty(128, 128, false, Image.FORMAT_RGB8)
    if i % 3 == 0:
        image.fill(Color.RED)
    elif i % 3 == 1:
        image.fill(Color.GREEN)
    else:
        image.fill(Color.BLUE)
    images.push_back(image)

# Create and save a 2D texture array. The array of images must have at least 1 Image.
var texture_2d_array = Texture2DArray.new()
texture_2d_array.create_from_images(images)
ResourceSaver.save(texture_2d_array, "res://texture_2d_array.res", ResourceSaver.FLAG_COMPRESS)

# Create and save a cubemap. The array of images must have exactly 6 Images.
# The cubemap's images are specified in this order: X+, X-, Y+, Y-, Z+, Z-
# (in Godot's coordinate system, so Y+ is "up" and Z- is "forward").
var cubemap = Cubemap.new()
cubemap.create_from_images(images)
ResourceSaver.save(cubemap, "res://cubemap.res", ResourceSaver.FLAG_COMPRESS)

# Create and save a cubemap array. The array of images must have a multiple of 6 Images.
# Each cubemap's images are specified in this order: X+, X-, Y+, Y-, Z+, Z-
# (in Godot's coordinate system, so Y+ is "up" and Z- is "forward").
var cubemap_array = CubemapArray.new()
cubemap_array.create_from_images(images)
ResourceSaver.save(cubemap_array, "res://cubemap_array.res", ResourceSaver.FLAG_COMPRESS)