for instance a bark texture dont need to be 4096 by 4096 thats a waist of space , if i use 4096 height and wide 2048 can be possible if we are talking about bark textures?
thanks
It is possible. Only power of 2 dimensions are required, no matter if value for height is different from width.
Thanks man thats what i need 
Another thing i was looking is the folder structure should be … Content/pack of name folder/materials,textures,meshes…Those 3 goes inside pack content name …but where i put the demo of the scene? should i create another folder that says demo_level?
I guess create a new folder in my asset pack that says maps , i guess
You create a folder called Maps and inside it you can create two level maps: 1 you can name it Showcase or Demo if you have a scene and 1 you can name it Overview and you will place all assets which are part of the package over a platform. If you are only distributing materials/textures you will only need an Overview map inside your Maps folder.
I would suggest for you do download from the Marketplace the Automotive Materials (free Epic’s content) and see how it is done the Overview map.