Expression to link a keyframe of alayer to out poin of other layers

[Andrei Popa]

I think the closest you can get with this is put an opacity expression to the layer that you want to make invisible. Something close to this. Here we take key 1 of property Scale of layer Reference layer

var keyframeProp = thisComp.layer("Reference layer").property("Scale");
var t = keyframeProp.key(1).time;
time < t ? value : 0;