How can I reduce the RMS value for a bridge rectifier?
You could simply add a couple of diodes to drop the voltage:







simulate this circuit &ndash; Schematic created using CircuitLab

each diode will drop about 1 V, you can add more if needed.

The "proper" way to do this is of course to use a transformer with the right output voltage. This diode trick is a bit of a "hack" but that might be all you need.