public static int maxTextureSize { get; }

The largest texture width and height that your graphics hardware supports.

Unity only supports textures up to a size of 16384, even if returns a larger size.

You can only create a texture with the maximum size if you have enough memory. For example, you need 1 gigabyte of memory to create a texture with a size of 16384, because the amount of data is 4 bytes per pixel × 16384 × 16384.