How to scale a model to the exact size of a part of another model?

I need to scale a model to the exact size of a part of another model by vertex. I can align the model to the other by pressing V key and snap the model position to the vertex of the other model but the same don’t work for scale. Each time I have to open the other model and measure the size of the part and then in UE I have to compute the scale. I hope there is a way for scale to snap to the vertex of the other model as it is possible to do for position. Thanks!