3 Phase potentiometer
The 3 phase pots can rotate the 3 inputs to any phase output.

The pots might be called 3 phase resolvers. Similar 2 phase Sin/Cos Pots exist for rotating phase in quadrature for rotating any signal by phase 0 to 360 deg.

3 phase pots continuously variable are expensive so other methods of phase-shifting can be done cheaper.


anecdote
In the 70's we used servo controlled sin/cos pots to shift the phase of calibration eddy current signals to produce 0 and 90 deg phase shifts for 1mm holes and 0.5mm change in wall thickness. A non-defect could then be displayed on an XY scope as a dot for impedance. The vector result of signals could then detect the type and size of an eddy current defect of the metal crystalline structure of a 1mm thick tube used to carry superheated heavy water.  This was done by robotics during annual maintenance to detect strain of tubing to prevent a leak of expensive heavy water under many kilo-atmospheres of pressure in 0.2mm increments over every 20m tube. (thousands per boiler)
This method was equivalent to measuring the change of a coil vector impedance more than 10 ppm.