Offset phase angle of AC mains?
Providing you don't want excessive amounts of power use a series inductor and a capacitor down to the return path from the inductor output. Depending on values, you should be comfortably be able to lag the voltage a few degrees: -



It's probably advisable to put a resistor of a few tens of ohms in series with the inductor in case of AC transients causing a resonant overshoot and possible destruction of the capacitor. The circuit forms a 2nd order low pass filter and there are plenty of examples on the internet about its general phase angle performance like this. I entered R=330\$\Omega\$ L = 100mH and C = 4.7uF. I reckon there was a lag of about 3º at 50Hz.

Using this technique to get leading output voltages is more tricky as you will need a relatively large inductor. Probably not advisable.

Whatever method you ultimately use you'll need to calculate currents and power disippation for the resistor.