How to create a gradient for a Mesh3d?

[KurlykovDanila]

I need to use not a color for the texture, but a gradient, for example, so that the texture gradually becomes transparent (gradient on the alpha channel). However, everything I could find with a gradient is either related to ui, or it cannot be used as a material or passed to a shader (ColorCurve). In this regard, the question is, is there a standard material that supports something like ColorCurve?