Single Element Voltage Reducer
If you:


Know your load characteristics and these remain relatively constant. 
You don’t care too much about load regulation, eg. 80V or 90v is the same to you. 
You don’t care that removing the load puts through the whole 120V at the output. 
Isolation is not important for the application. 


Then any series element that has a voltage drop when an AC current flows through it will do the trick. Assuming you want to remain linear and not distort the AC waveform, then your obvious choices are a resistor, a capacitor, or an inductor. Any of them will create a voltage divider with your load. 

A 30W load at 85V implies a real impedance (resistance) of 240ohm and a current of 350mA. So, to produce a drop of 35V all you need is an impedance of 100ohm. 


A 100ohm resistor will do it, but it will be dissipating 12W in the process. 
At 60Hz, a 265mH inductor would do it with no power dissipation. 
At 60Hz, a 26uF capacitor would do it, with no power dissipation. 


There are many more options that involve other compromises, but it can’t get simpler than this. 



But without a load (and a multimeter presents a load, a small one but a load nonetheless) the problem becomes physically impossible. 

One of the lesser known laws of physics is the conservation of information. To achieve the desired goal the mystery material would need to break this law. 

Let’s consider the DC case. In that case the solution is easy, place a battery or any other element that can maintain an electric field (e.g., a charged capacitor) and you obtain your desired result. So, what makes the AC case impossible? Why can’t we come up with an AC battery to solve the problem?

By making the problem AC, two new pieces of information are added that are not present in the DC case. The frequency and the phase. The mystery element knows nothing of either of those, unless it can access the other wire. 

In the above I simply assumed the frequency as a given (and the resistor does not care), but this still leaves the phase as an unknown.  This information is only provided to the mystery element via the circulating current when the load is attached. 

It is quite possible to design an “AC battery”, that maintains a stable voltage across its leads, but it would need a circulating current (a load) so that it can synchronize its frequency and phase to that of the source.