Render model on top of one specific model but behave normal to all other models

Is it possible to have a custom shader paired with a script to render a model in front of one specific other model but behave in a normal way (renderered behind, if behind) to other models. To illustrate what i want to achieve i attached a sketch. I want to render number 3 in front of number two but behind number 1. Is it maybe possible to use tags or layers to achieve this? I am pretty much a newby when it comes to shaders.

I already found some shaders that allow me to render one model ontop of all other ones but I couldn't find one that does what i need.