Thank you! I'm glad you like it! My English is not very good, I will still try to answer your questions. The sizes depend on the amount of detail of the tile or the piece. All the pieces have a potential size of 2, that is 32, 64, up to a maximum of 8192 (to optimize the performance of your game).
However, in the Itch store, there are only graphics and music. There are no animations, because that is included in the Unity scene, so itch comes at a cheaper price. If you buy the project in the Unity store it incorporates animations of trees, particles, fire, rain, etc. I leave the link here: https://assetstore.unity.com/detail/2d/environments/1803-hq-magical-world-bundle-backgrounds-hand-painted-156836
Remember in Unity it costs a little more expensive! : )