Blend/Mix/Morph 2 differnt Zones or Layers

Hi there,
maybe this is asked before but I can’t find an answer.

I Like to know if it is possible to mix, blend or morph 2 different Layers or Zones together with only one Knob or Slider and how does it work.
For Example:
30% from a Synth - 70% from a Sample
X% from one Sample - X% from another Sample
2 different Synth together.

Thanks for help.